question

cells

answer

- smallest living units in the human body - only about 0.1 mm in diameter

question

cell theory

answer

- cells are the building blocks of all plants and animals - all cells from from the division of preexisting cells - cells are the smallest units that perform all vital physiological functions - each cell maintains homeostasis at the cellular level

question

cytology

answer

- study of cellular structure and function - is part of a broader discipline of cell biology

question

cell biology

answer

integrates aspects of biology, chemistry, and physics

question

2 classes of cells

answer

sex and somatic

question

sex cells

answer

- aka germ cells/ reproductive cells - either sperm cells of males or the oocytes of females

question

somatic cells

answer

include all the other cells, besides sex cells, in the human body

question

plasma membrane

answer

- aka cell membrane - outer boundary of the cell

question

functions of the cell membrane

answer

1) physical isolation- physical barrier that separates the inside of the cell from the surrounding extracellular fluid 2) regulation of exchange with the environment- controls the entry ions and nutrients 3) sensitivity to the environment- first part of the cell affected by changes in the composition 4) structural support- specialized connections between the membrane and extracellular materials, gives tissues stability

question

phospholipid bilayer

answer

- phospholipid molecules forms 2 layers - ex: plasma membrane

question

phospholipid

answer

- hydrophilic end -> phosphate portion - hydrophobic end -> lipid portion

question

2 classes of membrane proteins

answer

1) integral proteins 2) peripheral proteins

question

integral proteins

answer

- aka transmembrane proteins because spans the width o the membrane one or more times - part of the membrane structure and cannot be removed without damaging or destroying the membrane

question

peripheral proteins

answer

bound to the inner and outer surface of the membrane and are easily separated from it

question

examples of functional proteins

answer

1) anchoring proteins 2) recognition proteins 3) enzymes 4) receptor proteins 5) carrier proteins 6) channels

question

anchoring proteins

answer

- attach the plasma membrane to other structures and stabilize its position - inside the membrane proteins are bound to the cytoskeleton - outside the cell to extracellular protein fibers or to another cell

question

cytoskeleton

answer

a network of supporting filaments in the cytoplasm

question

recognition proteins (identifiers)

answer

- cells of the immune system recognize other cells as normal or abnormal on the presence of absence of the cells - ex: glycoproteins

question

enzymes

answer

- in plasma membranes may be integral or peripheral proteins - catalyze reactions depending on the location of the protein and its active site

question

receptor proteins

answer

- in plasma membrane are sensitive to the presence of specific extracellular molecules called ligands - differ from cell to cell

question

ligands

answer

- can be small from a ion, to a relatively large and complex hormone - binds to the appropriate receptor, which triggers changes in the activity of the cell

question

carrier protein

answer

-bind solutes and transport them across the plasma membrane - may require ATP as an energy source

question

channels

answer

- central pore in some integral proteins that forms a passageway completely across the plasma membrane - permits the movement of water and small solutes across the plasma membrane - many are highly specific and permit the passage of only one particular ion

question

rafts

answer

mark the location of anchoring proteins and some kinds of receptor proteins

question

glycocalyx

answer

- carbohydrate portions of large molecules (such as proteoglycans, glycoproteins, and glycolipids) that extend beyond the outer surface of the membrane

question

functions of glycocalyx

answer

1) lubrication and protection- glycoproteins and glycolipids form a viscous layer that lubricates and protects the plasma membrane 2) anchoring and locomotion- the components are sticky, so help anchor the cell in place. Also, takes part int he locomotion of specialized cells 3) specificity in binding- glycoproteins and glycolipids can function as receptors, binding specific extracellular compounds 4) recognition- cells involved with the immune response recognize glycoproteins and glycolipids as normal or abnormal

question

cytoplasm

answer

- general term for the material located between the plasma membrane and the membrane surrounding the nucleus - contains cytosol and organelles

question

cytosol

answer

- aka intracellular fluid - contains dissolved nutrients, ions, soluble and insoluble proteins, and waste product

question

organelles

answer

structures suspended within the cytosol that perform specific functions for the cell

question

differences between cytosol and extracellular fluid

answer

1) concentration of potassium ions is higher in cytosol; whereas concentration of sodium ions lower in cytosol 2) cytosol contains higher concentration of suspended proteins 3) cytosol usually contains small quantities of carbs, and small reserves of amino acids and lipids. Extracellular fluid is transport medium only, and no reserves stored there. 4) both are within tissues

question

inclusions

answer

- masses of insoluble materials in cytosol - ex: glycogen, melanin, carotene

question

organelles

answer

internal structures that perform most of the tasks that keep a cell alive and functioning - has specific functions related to cell structure, growth, maintenance, and metabolism

question

2 catergories of cellular organelles

answer

1) nonmembranous 2) membranous

question

nonmembranous organelles

answer

- completely enclosed by membranes and all their components are in direct contact with the cytosol - ex: cytoskeleton, micovilli, cantrioles, cilia, ribosomes, and proteasomes

question

membranous organelles

answer

- isolated from cytosol by phosphlipid membrane, just as the plasma membrane isolates the cytosol from the extracellular fluid - ex: endoplasmic reticulum, golgi apparatus, lysosomes, peroxisomes, and mitochondria, nucleus (also surrounded by a membranous envelope and therefore a membranous organelle)

question

cytoskeleton

answer

- functions as the cells skeleton - provides an internal protein framework that gives the cytoplasm strength and flexibility - plays a role in the metabolic organization of the cell by determining where in the cytoplasm key enzymatic reactions occur and where specific proteins are synthesized - ex: micofilaments, intermediate filaments, and micotubules

question

microfilaments

answer

- smallest of the cytoskeletal elements - typical ones are composed of the protein actin

question

functions of microfilaments

answer

1) anchor cytoskeleton to integral proteins of the plasma membrane 2) determine the consistency of the cytoplasm 3) actin interacts with the protein myosin to produce movement of a portion of a cell or to change the shape of the entire cell

question

functions of intermediate filaments

answer

1) strengthen the cell and help maintain its shape 2) stabilize the positions of the organelles 3) stabilize the position of the cell with respect to surrounding cells through specialized attachment to the plasma membrane

question

intermediate filaments

answer

- size: between microfilaments and thick filaments - insoluble, and are the most durable of the cytoskeletal elements

question

microtubules

answer

- hollow tubes built from the globular protein tubulin - largest components of the cytoskeleton

question

centrosomes

answer

micotubules that extend outward into the periphery of the cell from a region near the nucleus

question

functions of microtubules

answer

1) form primary components of cytoskeleton, giving the cell strength and rigidity and anchoring the position of major organelles 2) disassembly provides a mechanism for changing the shape of the cell 3) serve as a monorail system to move vesicles or other organelles within the cell 4) during cell division microtubules form the spindle apparatus 5) form structural components of organelles such as centrioles and cilia

question

molecular motors

answer

- proteins that effect the movement of vesicles or other organelles - ex: kinesin and dynein carry materials in opposite directions on a microtubule

question

spindle apparatus

answer

distributes duplicated chromosomes to opposite ends of the dividing cell

question

thick filaments

answer

- relatively massive bundles of subunits composed of the protein myosin - appear only in muscle cells, where they interact with actin filaments to produce powerful contractions

question

microvilli

answer

- small, finger-shaped projections of the plasma membrane on their exposed surfaces - greatly increase the surface area of the cell exposed to the extracellular environment

question

centrioles

answer

- cylindrical structures composed of shot microtubules - all animal cells capable of undergoing cell division contain them (cells without them cannot divide: ex red blood cells, skeletal muscle cells, cardiac muscle cells, and typical neurons) - form 9 groups (3 in each)

question

9+0 array

answer

- formation of 9 groups of centrioles with 3 in each group - connected to its nearest neighbors on either side - no central microtubules

question

centrosomes

answer

- the cytoplasm surrounding teh centrioles - heart of the cytoskeletal system

question

cilia

answer

- long, slender extensions of the plasma membrane - found on cells lining the respiratory and reproductive tracts - beat rhythmically to move fluids or secretions across the cell surface - internal arrangement similar to centrioles - 9 pairs of microtubules

question

9+2 array

answer

nine pairs of microtubules surround a central pair

question

power stroke

answer

cilia is relatively stiff

question

return stroke

answer

cilia is flexible during the return stroke

question

ribosomes

answer

- organelles responsible for protein synthesis - about 60% RNA and 40% protein

question

2 subunits of functional ribosomes

answer

1) small ribosomal subunit 2) large ribosomal subunit - both contain special proteins and ribosomal RNA (rRNA)

question

what must happen for protein synthesis to begin?

answer

a small and a large ribosomal subunit must join together with a strand of messenger RNA (mRNA)

question

2 types of functional ribosomes

answer

1) free ribosomes 2) fixed ribosomes

question

free ribosomes

answer

-scattered throughout the cytoplasm - proteins that manufacture the cytosol

question

fixed ribosomes

answer

attached to the endoplasmic reticulum

question

endoplasmic reticulum (ER)

answer

- a network of intracellular membranes connected to the nuclear envelope, which surrounds the nucleus - membranous organelle - proteins manufactured by fixed ribosomes enter where they are modified and package for secretion

question

proteasomes

answer

- organelles that contain an assortment of protein-digesting (proteolytic) enzymes - remove damaged or denatured proteins from the cytoplams by disassembling them into amino acids and small peptides - breaks down abnormal proteins, such as those produced within cells infected by viruses - also play key role in immune response

question

4 functions of the ER

answer

1) synthesis: special areas synthesize proteins, carbs, and lipids 2) storage: sore synthesized molecules or materials absorbed from the cytosol without affecting other cellular operations 3) transport: travel from place to place 4) detoxification: absorbed and neutralized within it

question

smooth endoplasmic reticulum (SER)

answer

- no ribosomes are associated with it - in muscles cells, neurons, and many others it also adjusts the composition of the cytosol by absorbing and storing ions, such as Ca2+ or larger molecules -in liver and kidney cells responsible for the detoxification or inactivation of drugs

question

functions of SER

answer

- synthesis of the phospholipids and cholesterol needed for maintenance and growth of the plasma membrane, ER, nuclear membrane, and golgi apparatus in all cells - synthesis of steroid hormones (ex: androgens and estrogens) in reproductive hormones - synthesis and storage of glycerides, especially triacylglycerides, in liver cells and adipocytes - synthesis and storage of glycogen in skeletal muscle and liver cells

question

rough endoplasmic reticulum (RER)

answer

- where many newly synthesized proteins are chemically modified and packaged for export to the golgi apparatus - outer surface are fixed ribosomes which gives it a beaded, grainy, rough appearance - most of the proteins and glycoproteins are packaged into small membranous sacs

question

transport vesicles

answer

small membranous sacs that are pinched off from the tips of the cisternae

question

golgi apparatus

answer

-receives a newly synthesized protein or glycoprotein from the RER that is destined for export from the cell - consist of 5 or 6 flattened membranous discs

question

cisternae

answer

flattened membranous discs

question

3 functions of the golgi apparatus

answer

1) modifies and packages secretions, such as hormones or enzymes, for release through exocytosis 2) renews or modifies the plasma membrane 3) packages special enzymes within vesicles for use in the cytoplasm

question

lysosomes

answer

- special vesicles that provide an isolated environment for the potentially dangerous chemical reactions - produced at the golgi apparatus and contain digestive enzymes

question

functions of lysosomes

answer

- primary contain inactive enzymes - secondary are form when primary fuse with membranes of damages organelles and activate the enzyme which then breakdown the lysosomal contents which allows the cell to protect itself against harmful substances and obtain valuable nutrients - function in destruction of bacteria by enclosing the substance in a small portion of the plasma membrane and then pinching it off to form a transport vesicle - performs essential cleanup and recycling inside the cell

question

endocytosis

answer

transporting substances into the cell

question

autolysis

answer

enzymes rapidly destroy the cell's proteins and organelles

question

lysosomal sotrage disease

answer

- serious disease affecting children - the lack of specific lysosomal enzyme results in the buildup of waste products and debris normally removed and recycled by lysosomes

question

peroxisomes

answer

- new are produced by the growth and subdivision of already existing ones - absorb and breakdown fatty acids and other organic compounds by generating hydrogen peroxide and having it broken down by catalase (enzyme inside it) - protects the cell from potentially damaging effects of free radicals produced during catabolism - highest in metabolically active cells

question

membrane flow

answer

- continuous movement and exchange of the RER, SER, golgi apparatus, and plasma membrane - provides a mechanism for cells to change the characteristics of their plasma membranes as they grow, mature, or respond to a specific environmental stimulus

question

mitochondria

answer

- organelles responsible for energy production - number varies with the cell's energy demands - have an unusual double membrane (outer surrounds the organelle, the inner contain cristae)

question

cristae

answer

numerous folds that increase the surface area exposed to the fluid contents of the mitochondrion

question

matrix

answer

fluid contents

question

what catalyzes the reactions needed for energy for cellular functions?

answer

metabolic enzymes

question

where does first step of AT production take place?

answer

in the cytoplasm

question

citric acid cycle

answer

- aka krebs cycle/ tricarboxylic acid cycle/ TCA cycle - enzymatic pathway that breaks down the absorbed pyruvate

question

aerobic metabolism

answer

- aka cellular respiration - mitochondrial activity that requires oxygen - prodices 95% of the ATP needed to keep a cell alive

question

nucleus

answer

- largest and most conspicuous structure in a cell - serves as the control center for cellular operations - determines the structure of the cell and functions it can perform by controlling which proteins are synthesized, under what circumstances, and in what amounts

question

nuclear envelope

answer

- double membrane that surrounds the nucleus and separates it from the cytosol - connected to RER

question

nuclear pores

answer

- allows chemical communication between the nucleus and the cytoplasm - each one contains regulatory proteins that govern the transport of specific proteins and RNA into or out of the nucleus

question

nucleoplasm

answer

- fluid contents of the nucleus - inside it is the nuclear matrix - also contains ions, enzymes, RNA and DNA nucleotides, small amounts of RNA and DNA

question

nuclear matrix

answer

a network of fine filaments that provides structural support and may be involved in the regulation of genetic activity

question

nucleoli

answer

- dark- staining area - transient nuclear organelles that synthesize ribosomal RNA and assemble risobomal subunits - form around portions of DNA that contain instructions for prducing ribosomal proteins and RNA when those instructions are being carried out

question

histones

answer

RNA, enzymes, and proteins that are in nucleoli

question

what stores instructions for protein synthesis in the nucleus?

answer

DNA

question

nucleosome

answer

a complex that is formed when DNA strands wind around the histones

question

chromatin

answer

tangle of fine filaments of nucleosomes that are loosely coiled within the nucleus in cells that are not dividing

question

chromosomes

answer

- tight coils of chromatin that form just before cell division begins - 23 pairs in somatic cells

question

genetic code

answer

- aka triplet code: a sequence of 3 nitrogenous bases specifies the identity of a single amino acid. So the information that is encoded must be read in groups of 3 - chemical "language" the cell uses - information is stored in the sequence of nitrogenous bases along the length of the DNA strand (adenine, thymine, cytosine, and guanine)

question

gene

answer

- functional unit of heredity - contains all the DNA triplets needed to produce specific proteins

question

gene activation

answer

- before a gene can affect a cell, the portion of the DNA molecule containing that gene must be uncoiled and the histones temporarily removed - begins with the temporary disruption of the weak hydrogen bonds between the nitrogenous bases of the 2 DNA strands and the removal of the histone that guards the promoter

question

promoter

answer

- aka control segments - at the start of each gene - the "read me", "don't read me", and "start" signals

question

what binds to the promoter of the gene?

answer

RNA polymerase

question

transcription

answer

- the synthesis of RNA from a DNA template - first step in the process of the binding of the gene and RNA polymerase - "to copy" or "rewrite"

question

messenger RNA

answer

information of DNA copied to it, which can leave the nucleus and carry the information to the cytoplasm, where protein synthesis occurs

question

coding strand

answer

strand containing the triplets that specify the sequence of amino acids in the polypeptide

question

template strand

answer

- contains complementary triplets that will be used as the template for mRNA production - resulting mRNA will have a nucleotide sequence identical to the coding strand, but with uracil instead of thymine

question

immature mRNA

answer

- aka pre-mRNA - mRNA strand assembled during transcription

question

RNA processing

answer

- editing of pre-mRNA before it leaves the nucleus to direct protein synthesis - nonsense regions are snipped out and the remaining coding segments are spliced together

question

introns

answer

nonsense regions that are sipped out

question

exons

answer

remaining coding segments that are not snipped out in RNA processing

question

protein synthesis

answer

- the assembling of functional polypeptides in the cytoplasm - occurs through translation

question

translation

answer

- the formation of the linear chain of amino acids, using the formation provided by an mRNA - message written in the "language" of nucleic acids is translated by ribosomes into the "language" of proteins - each codon along the mRNA strand binds a complementary anticodon on a tRNA molecule

question

transfer RNA (tRNA)

answer

relatively small and mobile type of RNA

question

anticodon

answer

bonds complementarily with an appropriate mRNA codon

question

start codon

answer

- first codon of the mRNA strand - always has the base sequence AUG

question

polyribosome

answer

series of ribosomes attached to the same mRNA strand

question

2 levels of nuclear control of cell structure and function

answer

1) DNA of molecules has direct control over the synthesis of structural proteins, and secretory products. Can alter the internal structure of the cell, its sensitivity to substances, or its secretory functions. 2) DNA of the nucleus has indirect control over all other aspects of cellular metabolism, because it regulates the synthesis of enzymes.

question

permeability

answer

the property of the plasma membrane that determines precisely which substances can enter or leave the cytoplasm

question

impermeable

answer

membrane through which nothing can pass

question

freely permeable

answer

membrane through which any substance can pass without difficulty

question

selectively permeable

answer

permits free passage of some materials and restricts the passage of others

question

2 methods of passage across the membrane

answer

passive or active

question

passive processes

answer

move ions or molecules across plasma membrane with no expenditure of energy by the cell

question

active processes

answer

require that the cell expend energy, generally in the form of ATP

question

3 categories of transport processes

answer

diffusion, carrier-mediated, and vesicular transport

question

diffusion

answer

- results from the random motion and collisions of ions and molecules (substance in an area of high concentration moves to an area of low concentration) - passive process

question

concentration gradient

answer

difference between the high and low concentrations

question

factors that influence diffusion rates

answer

- distance: shorter= faster - molecule size: smaller= faster - temperature: higher the temperature= faster - concentration gradient: larger= faster - electrical forces: opposite attract and like repel

question

electrochemical gradients

answer

the net results of the chemical and electrical forces acting on an ion

question

how can an ion or molecule diffuse across the plasma membrane?

answer

1) crossing the lipid portion of the membrane 2) passing through a membrane channel

question

simple diffusion

answer

- diffuse through the lipid portions of the membrane - ex: alcohol, fatty acids, and steroids

question

channel-mediated diffusion

answer

uses a membrane channel for diffusion

question

membrane channel

answer

- small passageways created by transmembrane proteins - water can pass easily, but even a small organic molecule is to big to fit through the channels

question

leak channels

answer

- aka passiave channels - remain open and allow the passage of ions across the plasma membrane

question

osmosis

answer

- net diffusion of water across a membrane - total coencentration of dissolved ions and molecules on either side of the plasma membrane stays the same - greater the initial difference in solute concentrations, the stronger the flow - eliminates solute concentration differences faster than solute diffusion

question

3 basic characteristics of osmosis

answer

1) diffusion of water molecules across a selectively permeable membrane 2) occurs across a selectively permeable membrane that is freely permeable to water, but not freely permeable to solutes 3) water flows across a selectively permeable membrane toward the solution that has the higher concentration of solutes, because that is where the concentration of water is lower

question

osmotic pressure

answer

an indication of the force with which pure water moves into that solution as a result of its solute concentration

question

hydrostatic pressure

answer

pushing against a fluid

question

aquaporins

answer

water channels

question

osmolarity

answer

- aka osmotic concentration - total solute concentration in an aqueous solution

question

tonicity

answer

- effects of various osmotic solutions on cells - how the solution affects a cell

question

isotonic

answer

a solution that does not cause an osmotic flow of water into or out of a cell

question

hypotonic

answer

water will flow into the cell causing it to swell up like a balloon

question

hemolysis

answer

cell bursting releasing its contents

question

hypertonic

answer

a cell loses water by osmosis

question

crenation

answer

shrinking of red blood cells

question

normal saline

answer

solution which approximates the normal osmotic concentration of extracellular fluids

question

dextran

answer

- carb that cannot cross a plasma membrane - elevate the osmolarity of the blood

question

carrier-mediated transport

answer

- requires specialized integral membrane proteins binds specific organic substances and carry them across the plasma membrane - can be active or passive

question

vesicular transport

answer

- involves the movement of materials within small membranous sacs - always an active transport

question

characteristics all forms of carrier-mediated transport have

answer

- specificity: binds and transports only certain substances - saturation limits: availability of substrate molecules and carrier proteins limits the rate of transport into or out of the cell - regulation: binding can affect the activity of carrier proteins

question

cotransport

answer

- aka symport - the carrier transports 2 substances in the same direction simultaneously, either into or out of the cell

question

countertransport

answer

- aka antiport - one substances moves into the cell and the other moves out

question

facilitated diffusion

answer

- insoluble lipids and and substances to large to fit through membrane channels can be passively transported across the membrane by carrier proteins - ATP expended

question

active transport

answer

- high energy bond provides the energy needed to move ions or molecules across the membrane - offers 1 great advantage: not dependent on a concentration gradient (cell can import or export specific substances, regardless of their intracellular or extracellular concentrations)

question

ion pumps

answer

- carrier proteins in all cells - actively transport the cations sodum (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) across their plasma membranes

question

exchange pump

answer

the carrier protein that transports 2 substances at the same time in countertransport

question

sodium-potassium exchange pump

answer

- exchanges intracellular sodium for extracellular potassium - for each ATP molecules consumed, three sodium ions are ejected and two potassium ions are reclaimed by the cell

question

secondary active transport

answer

- moves a specific substrate down its concentration gradient - also move another substrate at the same time, without regard to its concentration gradient (second one gets a "free ride")

question

vesicular transport

answer

- materials move into or out of the cell in vesicles - 2 categories: endocytosis and exocytosis

question

vesicles

answer

small membranous sacs that form at, or fuse with, the plasma membrane

question

bulk transport

answer

tiny droplets of fluid and solutes are transported either than single molecules

question

endocytosis

answer

- extracellular materials packaged in vesicles at the cell surface and imported into the cell - involves relatively large volumes of extracellular material and requires energy in the form of ATP

question

3 types of endocytosis

answer

- receptor- mediated, pinocytosis, and phagocytosis - all are active processes that require ATP

question

receptor-mediated endocytosis

answer

- produces vesicles that contain a specific target molecule in high concentration - begins when materials in the extracellular fluid binds to receptors on the membrane surface

question

ligand

answer

target

question

coated vesicles

answer

- endosomes that are produced when an area of the plasma membrane becomes covered in ligands, it forms grooves or pockets that move to one area of the cell and then pinch off to form an - protein-fiber that originally carpeted the inner membrane surface beneath the receptor-ligand clusters now surrounds them

question

endosomes

answer

a processing and sorting vesicles

question

pinocytosis

answer

- "cell drinking" - formation of endosomes filled with extracellular fluid - no receptors are involved - target appears to be the fluid contents in general

question

phagocytosis

answer

- "cell eating" - produces phagosomes containing solid objects - cytoplasmic extension surround the object and their membranes fuse to form a phagosome - performed only by specialized cells

question

pseudopodia

answer

cytoplasmic extensions that surround and object to make phagosomes

question

exocytosis

answer

- functional reverse of endocytosis - vesicle created inside the cell fuses with, and becomes part of, the plasma membrane - the vesicle contents are then released into the extracellular environment - common in cells lining capillaries

question

does the inside of the plasma membrane have a positive or negative charge?

answer

negative, due to the excess of positive charges outside the plasma membrane and excess of negative inside

question

potential difference

answer

exists between positive and negative changes when they are held apart

question

transmembrane potential

answer

potential difference across a plasma membrane

question

volt (V)

answer

unit measurement of potential difference

question

resting potential

answer

- transmembrane potential in an undisturbed cell - each cell has one between -10 mV and -100 mV (- sign signifying the inside of plasma membrane has excess negative charges)

question

what would happen to the potential difference if the lipid barrier were removed?

answer

the positive and negative charges would rush together and it would be eliminated

question

potential energy

answer

stored energy that can be released to do work

question

cell division

answer

form of cellular reproduction

question

daughter cells

answer

division of a single cell produces a pair, each half the size of the original

question

apoptosis

answer

genetically controlled death of cells

question

bcl-2

answer

gene that appears to prevent apoptosis and to keep a cell alive and functional

question

DNA replication

answer

duplication of the cell's genetic material

question

mitosis

answer

- nuclear division/ duplication of the chromosomes in the nucleus and their separation into 2 identical sets - occurs during division of somatic cells - stages: prophase, metaphase, anaphase, and telophase

question

meiosis

answer

the production of sex cells

question

what unwinds the DNA strands?

answer

enzymes called helicases

question

DNA polymerase

answer

- bind to the exposed nitrogenous bases of the unwinded strands of DNA - work in only 1 direction - on second strand works away from the unzipping site

question

ligases

answer

enzymes that splices the 2 segments of the DNA strands together

question

interphase

answer

- divided into G1, S, G2 phases

question

cytokinesis

answer

- division into 2 daughter cells - usually begins in late anaphase and continues throughout telophase - completion marks the end of cell division

question

start of mitosis

answer

chromosomes become condensed and highly visible

question

frequency of cell division

answer

estimated by the number of cells in mitosis at any time

question

mitotic rate

answer

- term used when discuss rates of cell division - longer the life expectancy of a cell type, the slower the rate

question

stem cells

answer

- relatively unspecialized - only function is the production of daughter cells (one daughter cell develops functional specialization while the other prepares for further division)

question

what does the rate of cell division balance?

answer

the rate of cell loss or destruction

question

M-phase promoting factor (MPF)

answer

- aka maturation- promoting factor - important internal trigger - assembled from 2 parts: cell division cycle protein called Cdc2 and a second protein called cyclin (when high appears int eh cytoplasm and mitosis gets under way)

question

cyclin

answer

levels climb as the cell life cycle proceeds

question

repressor genes

answer

genes the inhibit cell division

question

p53

answer

- controls a protein that resides in the nucleus and activates genes that direct the production of growth- inhibiting factors inside the cell - about 1/2 of all cancers are associated with abnormal forms

question

telomeres

answer

- regulates the number of cell division performed by a cell and its descendants - terminal segments of DNA with associated proteins

question

functions of telomeres

answer

- attach chromosomes to the nuclear matrix - to protect the ends of the chromosomes from damage during mitosis

question

tumor

answer

- aka neoplasm - mass or swelling produced by abnormal cell growth and division

question

benign tumor

answer

cells usually remain within the epithelium or connective tissue capsule

question

malignant tumor

answer

- cells no longer respond to normal control mechanisms - spread into surrounding tissues

question

primary tumor

answer

- aka primary neoplasm - tumor of origin

question

invasion

answer

spreading process of primary tumor

question

secondary tumors

answer

malignant cells that travel to distant tissues and organs and establish tumors

question

metastasis

answer

- dispersion of malignant cells - begins with invasion as tumor cells "break out" of the primary tumor and invade surrounding tissue

question

cancer

answer

illness characterized by mutations that disrupt normal control mechanisms and produce potentially malignant cells

question

oncogenes

answer

modified genes that become malignant

question

differentiation

answer

- development of specific cellular features - produces specialized cells with limited capabilities - these cells form organized collections known as tissues, each with discrete functional roles

Chap. 3 Cellular Level of Organization – Flashcards

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