Biology Midterm Study Guide – Pre-IB 9th Grade

Cell Theory
– cells are considered to be the basic unit of life
– all living organisms are composed of cells
– all cells come from pre-existing cells

– the study of cells

Prokaryotic Cells
– primarily bacteria, would have evolved before a nucleus had evolved into existence

Eukaryotic Cells
– would have evolved after a nucleus had evolved unto existence ‘
– 3 main parts: Plasma, Nucleus, Cytoplasm

Surface-to-Volume Ratio
– cells can only be so small because there has to be enough room to hold things and perform work in the cell
– cells can only be so large and still be efficient

– control center for activities performed by the cell
– the source of genetic information (DNA)

– cellular particles (all types of

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cells contain) made of ribosomal RNA, mRNA, and proteins
– site for Protein Synthesis

Endoplasmic Reticulum (ER)
– two types: Smooth Endoplasmic Reticulum (SER) and Rough Endoplasmic Reticulum (RER)
– helps with Protein Synthesis

Golgi Apparatus
– modifies proteins by attaching sugars to them (Glycoproteins)

– acts as ‘stomach’ for the cell
– involved in digestion and recycling of molecules
– intracellular and extracellular digestion

– storage structures for the cell

– the process of bringing something into the cell

– the process of the cell ‘eating’

– the process of the cell ‘drinking’

– ‘powerhouse’ of the cell
– involved in making energy by performing the process of cellular respiration inside it
– structure looks like ‘room within room’

– are the site of photosynthesis in plants and algae
– has it’s own DNA, ribosomes, and enzymes
– structure looks like ‘room within room’

Symbiotic Relationship
– hypothesized that Prokaryotes came to live together
– the smaller living inside the larger to gain protection over other prokaryotes and eventually they evolved into Eukaryotic cells (larger cell gained energy production)

– helps support and protect the cell, keeps the organelles organized, and helps in cell movement

Cell Wall
– plant cells create this structure for protection and durability

– make up the majority of the cell membrane
– amphipathic molecules

Integral Protein
– located in cell membrane
– amphipathic
– runs through the bilayer of the membrane from the outside to the inside
– function in the transport of molecules and foundation

Peripheral Protein
– not in plasma membrane
– located on one side of the membrane
– attachment points for the cytoskeleton and ECM

– helps keep the membrane of all cells flexible

Material Transport
– CO2 and O2 diffuse across the wet phospholipid bi-layer
– Ions and water move through the proteins

– materials flow from high [] to lot [] until equilibrium is reached
– how the majority of materials are transported in cells

– diffusion of water
– water always flows from from Hypotonic to Hypertonic until Isotonic (materials dissolved in water, not the water itself)

Facilitated Diffusion
– the movement of molecules that requires the help of a transport protein
– does not need energy to occur

Active Transport
– requires energy to occur
– this process is moving against the concentration [] gradient

– the process of moving materials out of a cell

– the process of moving material into a cell

Types of Signaling (Cells and Organisms)
– Direct (involves physical contact)
– Local (growth factors are released into into a localized area)
– Long Distance (Hormones are released in one part of the body and travel to another part/Pheromones (Chemical mate attractants released into the environment)

Signal Transduction Pathway
– Reception (chemical binding to membrane receptor protein)
– Transduction (a series of steps in the changing of the signal to something the cell can understand at the nucleus/cytoplasm)
– Response (involves making something or turning on/off an enzymatic process)

– signal molecule

G-Protein Pathway
– the most common pathway used by cells
– G-Protein Linked Receptor (serves as the attachment point for the Ligand)
– G-Protein (acts as a relay protein carrying the message to the appropriate location)

Tyrosine-Kinase Pathway
– pathway is involved with Growth/Emergency repair most od the time

Protein Kinase Cascades
– turn on processes by phosphorylating the molecule
– point of the cascade is to amplify the signal

Protein Phosphatase Cascades
– turn off processes by removing a phosphate ion form the molecule
– point of the cascade is to amplify the signal

Cellular Response
– is about the regulation of some cell process
– responses are usually protein synthesis or product synthesis

Amplification of the Signal
– only need small amount of the ligand to convey the message
– the cascades amplify the signal at each step

Cell Division
– parent cell results in 2 genetically identical daughter cells (offspring cells)
– the daughter cells are genetically identical to each other and the previous parent cell

Somatic Cells
– normal body cells
– make up the majority of an organism
– chromosomal content: diploid

– proteins that help DNA coil up to form the chromosomes needed for division

Sister Chromatids
– refers to half of a duplicated chromosome
– the two tables are held together at the centromere

– means nucleus division
– 4 parts:

– Cell Cycle Phase
– cells spend 90% of their existence in this phase
– this phase consists of three parts:
G1 (primary or first growth)
S (duplicated)
G2 (secondary or second growth)

– the division of the cytoplasm
– the cytoplasm and cell organelles are separated to produce two daughter cells

Cell Plate
– plant cells do not have centrioles because they have cell walls to anchor to
– develops using small segments of cellulose instead of a cleavage furrow

Binary Fission
– the process of Reproduction/Replication in prokaryotes

Regulation (of the Cell Cycle)
– is controlled by Cyclins
– three checkpoints exist

– 2 main types:
Benign (non-invasive, usually not deadly, and easy to remove the tumor)
Malignant (invasive, grows between cells destroying the tissue)

– anything that takes up space and has mass to it

– the simplest form of a substance that cannot be broken apart and still have the properties of that element

– two or more elements bonded together resulting in new chemical properties to emerge for that compound

– the most common elements in all life

– the smallest unit of matter with set chemical properties
– maintain their original properties because the subatomic parts are all present

Subatomic Particles
– small part the make up atoms

– carry a positive charge
– located in the nucleus of an atom
– the amount never changes in an element

– carry no charge
– located in the nucleus in an atom

– carry negative charge
– located outside the nucleus in ‘electron cloud’

– two or more atoms bonded together

Atomic Number
– refers to the number of protons in that element

Mass Number
– refers to the number of protons and neutrons together in that element or molecule

– atoms that possess different numbers of neutrons than the normal amount for that element
– usually have the same chemical properties as the normal element, the physical properties maybe different
– most are radioactive

– comes from the rapid movements of electrons normally, but it could be neutrons too

Potential Energy (PE)
– energy of position

Kinetic Energy (KE)
– energy of movement

Covalent Bond
– the strongest type of chemical bond
– always create a molecule

Ionic Bond
– strong bonds when dry, but are weak in water so they dissolve into ions:
Cations: possess a positive charge
Anions: possess a negative charge
(are polar molecules because they love water)

Hydrogen Bond
– weak bond
– most important biological bonds

– located on the left side of an equation

– located on the right side of an equation

– refers to water binding to other water molecules
– made possible because of Hydrogen bonds

– refers to water molecules binding to something other than water molecules
– made possible because of Hydrogen bonds

Surface Tension
– the linking together of water molecules on the surface of a body of water
– made possible because of Hydrogen bonds

Evaporative Cooling
– putting heat energy into water, causing the water to evaporate and carry the heat energy away from the body thus, providing a cooling of the organism to occur as the energy leaves
– wind increases the effect of cooling by carrying the water vapor away from the body. *Humidity* (Water vapor in the air, decreases the effect because water can’t evaporate in the air as it is already full of water vapor.)

– refers to water breaking into H+ (Proton) and an OH- (Hydroxide Ion)

pH Scale
– goes from 0-14
– 7 is neutral

– <7 on pH Scale

– >7 on pH Scale

– a substance that can resist changes in pH or pOH
– it can take on or gives off a H+ or OH- to maintain the pH or pOH concentration

Acid Precipitation
– refers to rain, snow, sleet, ice, or fog with a low pH

Organic Chemistry
– branch of science dealing with the element carbon and its many properties

– refers to most compounds not containing Carbon

Single Bond between Carbon Atoms
– C-C

Double Bond between Carbon Atoms
– C=C

Triple Bond between Carbon Atoms
– C=C (underscore under equal sign)

– molecules containing Carbon and Hydrogen
– most are energy sources

– are formed from monomers (linked together by covalent bonds)
– theme: Structure = Function

– formed by Dehydration or Condensation Reactions
(Hydroxyl (OH) is removed from one molecule and Hydrogen (H) is removed from another)
– this combination forms water
– this orientation of molecules and making of a bind requires E
– Enzymes help speed up the rate of the reaction

Hydrolysis Reaction
– releases energy in the bond breakage
– process needs water to full the ion bonds on the monomers
– enzymes help speed up the rate of the reaction

– the ‘unraveling’ of a protein or enzyme causing it not to function
– can be caused by pH changes, salt concentration, and temperature changes

DNA Double Helix
– Watson and Crick made the model
– the two sides are said to be complimentary
– one side has information to make proteins and enzymes (The Million Dollar Blueprint); other side is a protective cap for the Million Dollar Blueprint, it protects the sequence of nucleotides

Genes and Evolution
– the more nucleotide sequence ‘genes’ in a common; the more closely related the organisms are
– the fewer nuclide sequence ‘genes’ in common; the more distantly related they are

– the sum of all the chemical reactions occurring in an organism
– 2 separate phases

– this process refers to the breaking down of a molecule
– releases potential energy found in the chemical bond between monomers

– the assembly of molecules
– requires kinetic energy to position molecules in a away so as to create a chemical bond between monomers

First Law of Thermodynamics
– energy cannot be created nor destroyed, only transformed or transferred

Second Law of Thermodynamics
– every energy transfer increases the disorder of the universe

Gibbs Free Energy
– referred to as ‘free’ because energy is available to perform work

– made from ribose sugar and the nitrogen base Adenine
– when it converts to ADP, it gives off energy; ADP being converted to this requires energy

– the attaching of an unstable phosphorus ion to another molecule to make it unstable and thereby able to perform work

– Biological Catalysts (proteins that speed up and control the rat of a chemical reaction)
– they are recycles; they are not consumed by the reaction
– selective in what they will work with
– usually end with ‘ase’

Free E of Activation
– refers to the free energy used to start a chemical reaction in motion
– lowered by the action enzyme

– refers to the molecule that is being affected by the substrate

Active Site
– refers to the location where the chemical reaction(s) is taking place between the enzyme and substrate

– these slow down or stop the rate of the chemical reaction
– 2 types:
Competitive: compete for an active site and slow down the reaction (these molecules will be removed)
Non-competitive: attach somewhere other than the active site causing the snap of the active site to change so the substrate can’t fit into it (cause the reaction to stop completely)

Feedback Inhibition
– a product in excess shuts down the reaction that is taking place at an earlier point in the pathway
– prevents ‘waste’ of precious materials and energy by not making more of what is not needed at that time

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