question

What is an allele?

answer

A gene for single trait comes in alternate forms called alleles. Alleles can be considered either dominant or recessive. The recessive will not show up unless the dominant is not present.

question

Explain and define Mendel's principles

answer

Bred 29,000 pea plants and studied how seven traits were passed on. Came to 2 conclusions and 2 principles

question

Mendel's Conclusions

answer

1. Always inherit a pair of genes that control a trait, one from each parent 2. A gene for a single trait comes in alternate forms called alleles- either dominant or recessive

question

Dominant allele

answer

An allele that will always be expressed if present. [uses capital letter(s)]

question

Recessive allele

answer

An allele that will only be expressed in the absence of the dominant allele. [uses lower case letter(s)]

question

Define phenotype

answer

The allele that is being expressed - what is seen.

question

Define genotype

answer

The alleles you possess for a given trait- three types: Homozygous dominant, Homozygous recessive, and heterozygous

question

Homozygous Recessive

answer

Having two recessive alleles for a trait

question

Homozygous Dominant

answer

Having two dominant alleles for a trait

question

Heterozygous

answer

Having one dominant and one recessive allele for a trait

question

Law of Segregation (Mendel's 1st principle)

answer

Two alleles of any gene are on homologs that separate from each other in Anaphase of meiosis. Half sex cells get one allele, and the other half get the other.

question

Law of Independent Assortment (Mendel's 2nd principle)

answer

Homolog arrangement in Metaphase I is random, passing a maternal allele from one homolog does not affect any other homologous pair

question

Sex Linked Traits

answer

A trait that is only present on the 23rd homologous pair- the X or the Y. If a Y linked trait- will always appear since there is only ever one Y in the 23rd homologous pair (Male=xy, Female= xx)

question

Autosomal Dominant

answer

Trait is dominant: phenotype appears every generation, affected individual has at least one affected parent, affects both male and female

question

Autosomal Recessive

answer

Trait is recessive: phenotype can skip a generation, affected individual can have unaffected parents, affects both male and female

question

Complete Dominance

answer

Punnett Square- Dominant trait is ALWAYS dominant

question

Incomplete Dominance

answer

Phenotype is a blend of dominant and recessive alleles - pink carnation

question

Co-dominance

answer

Phenotype is both alleles, but not blended- more blotchy. Is often ENVIRONMENTALLY influenced

question

Multiple Alleles

answer

A gene that has more than two possible alleles- you can only inherit two, even if there are more than two possibilities

question

Pleiotropic

answer

One gene controls multiple different traits (opposite of polygenic)

question

Polygenic

answer

Multiple genes control the same trait (opposite of pleiotropic)

question

Chromatin

answer

Makes up Chromatids- make up chromosomes: Made of histone protines with strands of DNA wrapped around them twice.

question

DNA is a polymer made of ____ monomers

answer

Nucleotides

question

2 classes of nitrogenous bases

answer

1. Purines 2. Pyramidines

question

Purines

answer

Adenine and Guanine

question

Pyramidines

answer

Cytosine and Thymine

question

Railing of DNA made of...

answer

Alternating Carbohydrates and phosphates

question

Carbohydrates in "railing" of DNA is____ bonded to __

answer

Covalently bonded to "rungs" of nitrogenous bases

question

Rungs of DNA made of _____, ______ bonded

answer

Two nitrogenous bases, hydrogen-bonded together

question

Adenine always bonds with _____ (part of Chargoff's Rules)

answer

Thymine

question

Thymine always bonds with_____(part of Chargoff's Rules)

answer

Adenine

question

Guanine always bonds with _____(part of Chargoff's Rules)

answer

Cytosine

question

Cytosine always bonds with _____(part of Chargoff's Rules)

answer

Guanine

question

Chargoff's Rules say

answer

Which nitrogenous bases will bond together. Purines are always double ringed, while pyramidines are single-ringed. Base pair of 1 purine and 1 pyramidine. (consistent width) [If you have 40% adenine you must have 40% thymine which leaves 20% to other bases- ten each.]

question

Order of pairs of nitrogenous bases in DNA

answer

Variable- determines an individual's genetic code

question

Explain Chromosomes: (beads on a string)

answer

Parents physically pass on alleles for genes on chromosomes. Chromosomes are made of chromatin. Chromatin is comprised of nucleosomes. Clumps of histone proteins with strands of DNA wrapped around them twice.

question

DNA Replication

answer

In the S stage of interphase, enzyme helicase untwists/unzips DNA, therefore, breaking hydrogen bonds. Enzyme DNA polymerase attaches complimentary bases to each half of unzipped DNA and each new DNA strand is exact clone of original. Each chromosome has added a chromatid. (when you want to copy entire cookbook)

question

The Central Dogma

answer

DNA-->RNA -->Protein-->Phenotype.

question

A gene

answer

A section of DNA with a code to produce a single protein.

question

Analogy

answer

Cell's nucleus is a library, chromosomes are cookbooks, genes are the recipes (to make protein), alleles are different versions of the same recipe (to make a protein)

question

What is so important about the proteins made?

answer

It is the protein you make that gives your phenotype for any gene!!!

question

Explain Translation

answer

Translation is when proteins are produced. mRNA leaves the nucleus and travels to a ribosome with a list of amino acid ingredients it needs. Translated codon by codon, codon codes for amino acid. But mRNA can't actually grab them, so tRNA comes in to play. tRNA carries an amino acid on one end and an anticodon on the other.

question

tRNA...

answer

The molecule that transfers AA to mRNA is called the transferRNA. Each molecule carries a specific amino acid.

question

Anticodon

answer

An anticodon hydrogen bonds only with its mRNA complimentary codon. The codon/anticodon match ensures each mRNA only gets the AA it calls for. 3 bases at the end of tRNA is where the anticodon is- sticks to codon and delivers amino acid.

question

Translation Continued

answer

mRNA winds its way into a ribosome. A ribosome exposes one codon at a time. One by one, tRNA brings the proper AA to each codon of mRNA. The individual AA are connected through dehydration reactions to form a polypeptide. The polypeptide folds into 3D form and becomes a protein (which actually expresses your gene.)

question

Promoters

answer

Switches for your genes. If a gene is "on" RNA polymerase transcribes. There are start and stop switches. Two cells with exact same recipes may behave differently because of these promoters that start and stop/turn on and off at different times.

question

Exons

answer

*to remember: EX (as in EXpressed).* Exons are expressed- actually codes for a protein

question

Introns

answer

Introns is a section of DNA that does not code for anything.

question

Where are proteins made in a cell?

answer

Ribosomes!

question

mRNA

answer

A copy of the DNA's recipe that can travel to ribosomes. The mRNA is made in the process of transcription. mRNA is mobile and leaves the nucleus. mRNA is a small copy of a single gene. It has ribose sugar in its railing. mRNA is single stranded-it lacks base pairs. mRNA replaces thymine with a base called uracil.

question

Transcription

answer

Helicase unzips the section of DNA with the gene, breaking the hydrogen bonds. Though the strand is double, only one side of dna is important. An enzyme called RNA polymerase travels around the strand- taking free nucleoiteds (A to A etc.) and matching them up with complement. It does this until it reaches stop codon and mRNA is released, leaves nucleus and goes into cytosol.

question

Helicase

answer

Helicase untwists or unzips only the section of DNA that has the needed gene (recipe).

question

Watson and Crick

answer

Published short paper (groundbreaking). Walked around and picked up pieces of the puzzle (about DNA) and put it together as a model. They

question

DNA Structure

answer

Is a polymer. DNA is a double stranded helix comprised of paired nucleotide monomers. Railings are for support. Rungs made of two nitrogenous bases hydrogen-bonded together

question

Rosalind Franklin's discoveries

answer

Rosalind's images demonstrated a molecule with 2 strands twisted around each other and pairs of nucleotides stacked along the middle.

question

Nucleotides consist of (3 parts)

answer

A phosphate group, a deoxyribose sugar, nitrogenous base

question

How many nucleotides does each cell in your body, need?

answer

6 billion

question

Monohybrid Cross

answer

When you are crossing one gene.

question

Dyhybrid Cross

answer

When you are crossing two genes. Four possibilities: sixteen box punett square

question

In sex cells, how many alleles do you pass on for each gene?

answer

In each sex cell you only pass on one allele for each gene.

question

Protein Synthesis

answer

DNA to RNA to protein. DNA cannot leave the nucleus so we make a copy of the recipe that can travel- called mRNA (made in transcription).

question

When is DNA replication is used?

answer

In meiosis and mitosis

question

How many strands of chromatin are there in a human sperm cell?

answer

23

question

What is NOT a part of the nucleotide monomers that comprise DNA?

answer

Protein

question

If you are heterozygous for a trait, what are the odds of passing the recessive allele to your kids?

answer

50.00000%

question

Codons

answer

Three bases in a row. Each is a code for a single ingredient in building a protein-amino acid. Possible 64 codons on a codon chart.

question

Archibald Garrod

answer

In 1902, described the first (recessive) human Mendelian genetic disorder, alkaptonuria. Disease caused by a lack of an enzyme, homogenistic acid oxidase

question

Dominant trait

answer

The trait that appears in the F1 progeny

question

Recessive trait

answer

The trait that does not appear in F1 progeny

question

Phenotype

answer

The appearance or physical structures of an individual.

question

Genotype

answer

The genetic composition of an individual.

question

Homozygous

answer

A gene pair in which both the maternal and paternal gnes are identical (e.g. RR or rr).

question

Heterozygous

answer

A gene pair in which the paternal and maternal genes are different (e.g. Rr)

question

Gene

answer

the basic unit capable of transmitting characteristics from one generation to the next. It consists of a specific sequence of DNA or RNA that occupies a fixed position locus on a chromosome.

question

Allele

answer

one of two or more alternative forms of a gene, occupying the same position locus on paired chromosomes and controlling the same inherited characteristic

question

Mendel's First Law (The principle of independent segregation)

answer

Genes occur in pairs and at the time of gamete formation, one of each pair enters the gametes. Inferred from F1 x F1 crosses.

question

Mendel's Second Law (The principle of independent assortment)

answer

One gene pair segregates (sorts) independent of another gene pair.

question

Walter Flemming

answer

Described mitosis in 1879

question

Meiosis vs Mitosis

answer

Mitosis Metaphase 1: line up linearly; one chromatid from each chromosome in daughter cells
Meiosis Metaphase 1: line up pairs and duplicated chromosomes separate; then 2nd mitotic-like cell division

question

Alkaptonuria

answer

Defective homogenistic acid oxidase enzyme which is responsible for tyrosine degradation. Leads to build up in blood and excess in urine, can result in kidney stones. It was the first recessive Mendelian genetic disorder found in humans.

question

How is genetics about phenotype?

answer

Mendel could only infer genotype by observation of phenotypic properties of progeny.

question

F2 Phenotypic Ratio

answer

9:3:3:1

question

3 Scientists who independently confirmed Mendel's Work

answer

Hugo DeVries, Karl Correns, and Erich von Tschermak

question

Walter Sutton

answer

1902-He came up with the chromosome theory of inheritance (genes are carried from parents to their offspring on chromosomes). He observed that segregation of chromosomes during meiosis matched segregation of Mendel's traits or factors.

question

Beadle and Tatum

answer

Their work on Neurospora led credence to the hypothesis that genes coded for enzymes. The thought at the time was that genes were composed of amino acids and that " one gene one enzyme".

question

Fredrick Griffith

answer

showed that DNA can carry genetic specificity with his work on virulent and nonvirulant strains of streptococcus pneumoniae. Heating cells up until they died showed that genetic components not only remain intact, but are able to transfer to nonvirulant strains and undergo genetic recombination.

question

Oswald Avery

answer

Avery isolated DNA, showing that if it was added to R (rough nonvirulent) cells they would turn to S (smooth virulent) cells. The transforming ability of these fractions were stopped if deoxyribonuclease was added, while if ribonuclease or protease there was no difference in the fractions transforming ability.

question

Hershey and Chase

answer

Their work with radioactive phages (radioactive S in protein coat and P in DNA) confirmed that nucleic acids were the actual component of DNA.

question

William Astbury

answer

1938-Took the first x-ray diffraction of DNA.

question

Williams and Franklin

answer

1950s-High quality x-ray diffractions showed that DNA was a helical structure and composed of more than one polynucleotide chain.

question

Alexander Todd

answer

Showed that DNA was held together by 3' to 5' phosphodiester bonds.

question

Linus Pauling

answer

Showed that alpha helices of polypeptide chains provided the models for DNA structure.

question

Crick and Watson

answer

1953-Showed the complementary nature of DNA.

question

Vernon Ingram

answer

1956-Showed that sickle hemoglobin differs from normal hemoglobin by the change of one amino acid in the beta chain

question

What causes sickle cell anemia?

answer

At position 6, glutamic acid residue found in wild-type hemoglobin is replaced by valine on the S allele of the beta globin gene

question

Meselson ; Stahl

answer

Showed that DNA replication is a semiconservative process in which the single strands of the double helix remain intact (conserved) during a replication process where one parental strand seperates into two daughter molecules, one original, and one new (semi).

question

Meselson ; Stahl Experiment

answer

Used CsCl density gradient centrifugation in which the sedimentation forms bands. The density gradient seperated by heavy (bottom), hybrid (middle), light (top)

question

What distinguishes RNA from DNA?

answer

1) RNA contains ribose, which is identical to deoxyribose except for the presence of an additional OH (hydroxyl) group on the 2' carbon
2) RNA has no thymine but has the closely related pyrimidine uracil (has no methyl group CH3)

question

Torbjorn Caspersson & Jean Brachet

answer

Found that RNA is in same cellular compartment (cytoplasm) where protein synthesis occurs

question

Adapter Hypothesis of Crick

answer

Crick proposed that prior to incorporation into proteins, amino acids are first attached to specific adapter molecules, which possess unique surfaces that can bind specifically to bases on the RNA templates

question

Paul Zamecnik (early years)

answer

1953-developed cell free extracts for protein synthesis by using radioactive tagged amino acids to trace newly made proteins and then ultracentrifuged them for fractioning.

question

Paul Zamecnik & Mahlon Hoagland

answer

Discovered that prior to incorporation into proteins, amino acids are first attached to transfer RNA (tRNA)

question

Arthur Kornberg

answer

Showed that a specific polymerizing enzyme is needed to catalyze the linking of building-block precursors of DNA
Ultimately isolated DNA polymerase I, the enzyme used to replicate DNA

question

DNA Polymerase I

answer

Catalyzes the synthesis of new DNA strands
Removes the primers (RNA nucleotides) from 5' end and replaces them with DNA nucleotides
Requires DNA template to determine sequence of the DNA strand that it is synthesizing

question

What evidence suggests that DNA cannot be the template that directly orders amino acids?

answer

Protein synthesis occurs at sites where DNA is absent
a second information containing molecule is needed that obtains its genetic specificity from DNA

question

Transfer RNA (tRNA)

answer

A type of RNA that carries an amino acid from the cytoplasm to the ribosome for incorporation into a growing protein

question

Ribosomal RNA (rRNA)

answer

The most abundant type of RNA (85%)
Composed of two unequally sized units, that stick together or fall apart depending on ion concentration
Brings the tRNA-amino acid precursors into position where they can read of information provided by mRNA templates

question

Messenger RNA (mRNA)

answer

type of RNA that carries instructions from DNA in the nucleus to the ribosomal sites of Protein synthesis
can be read by several ribosomes

question

Polyribosomes

answer

A group of ribosomes translating the same mRNA

question

Why was mRNA overlooked?

answer

Because only a small percent of total cellular RNA is mRNA

question

Transcription

answer

RNA synthesis
Process by which a DNA template is used to produce a single-stranded RNA molecule

question

Translation

answer

Protein synthesis
genetic information coded in messenger RNA directs formation of specific Protein at ribosome in cytoplasm
Starts and stops at internal positions

question

Jerard Hurwitz ; Samuel Weiss

answer

Isolated the first RNA polymerase

question

RNA polymerase

answer

An enzyme that pulls the 2 strands of DNA apart and hooks together the RNA nucleotides as they base pair along the DNA template

question

Which experiment confirmed movement of mRNA from nucleus to ribosome-containing cytoplasm?

answer

Pulse labeling experiment

question

Pulse Labeling Experiment

answer

Briefly exposed cells to radiolabeled precursors, adding large excess of unlabeled nucleotides in which mRNA synthesized in short window of time
Study Showed that mRNA is synthesized in nucleus
Led to conclusion that direction of Protein synthesis from AA teminus to carboxyl terminus (new aa added to C terminus of growing poly chain)

question

Charles Yanofsky ; Sidney Brenner

answer

1960 - Conducted a mutational analysis on bacterial proteins that showed colinearity exists

question

Colinearity

answer

Concept that a gene's DNA codon sequence is the same as the protein's amino acid sequence along a given polypeptide chain

question

Brenner ; Crick

answer

1961 - First to establish that groups of three nucleotides are used to specify (code) individual amino acids

question

Marshall Nirenberg ; Heinrich Matthaei

answer

1961 - addition of synthetic polynucleotide poly U (UUUU...) to cell-free system capable of making proteins lead to synth of polypeptide chains w/ only AA phenylalanine

question

Har Gobind Khorana

answer

Used polynucleotides like AGUAGU to complete the genetic code

question

Completion of the Genetic Code revealed...

answer

1966 - Revealed that 61 out of 64 possible groups correspond to amino acids, with most amino acids being encoded by more than one nucleotide triplet.

question

Central Dogma

answer

DNA --> A: Transcription --> RNA --> B: Translation --> Protein

question

Synthetic Polynucleotides

answer

Poly U = Phenyl Alanine
Poly A = Lysine
Poly C = Proline

question

Nonsense codons

answer

Three codons that do not direct the addition of a particular amino acid but instead serve as translational stop signals (aka stop codon)
UAA, UAG, UGA

question

start codon

answer

AUG codon (methionine) in eukaryotes
AUG or GCG in prokaryotes
signals ribosomes to begin translation
Codes for the first amino acid in polypeptide chain

question

How does initiator AUG distinguish from an internal codon? Pro vs. Euk

answer

prokaryotes - AUG codons start new polypeptide chains, preceded by specific purine-rich blocks of nucleotides - serve to attach mRNA to ribosomes
eukaryotes - position of AUG relative to beginning of mRNA is critical determinant, w/ first AUG always selected as start site of translation

question

Comparative Genomics

answer

Identification of conserved and non-conserved DNA sequences between species, compare new genome sequence to previously sequenced genomes
Potential to identify mutations that lead to disease

question

what is a gene?

answer

discrete units of inheritance (segments of DNA)

question

what does a gene consist of?

answer

specific sequence of nucleotides in DNA

question

what is a chromosome?

answer

a single piece of coiled DNA containing many genes

question

what is DNA?

answer

a double strand polymer of nucleotides

question

3 main structures of DNA

answer

phosphate
5 carbon sugar (deyoxribose)
nitrogen base

question

what are the 4 different nitrogen bases of DNA?

answer

Adenine
Guanine
Thymine
Cytosine

question

Of the 4 nitrogen bases of DNA, which 2 are double ringed purines?

answer

Adenine and Guanine

question

of the 4 nitrogen bases of DNA, which 2 are single ringed pyrimidines

answer

thymine and cytosine

question

the phosphate and 5 carbon sugar combine to form what?

answer

phosphate-sugar complex

question

how are phosphate-sugar complexes bonded together?

answer

covalent bonds

question

how are the nitrogen bases bonded to the phosphate-sugar complexes?

answer

covalent bonds

question

How are the double strands of DNA bonded together?

answer

hydrogen bonds via the nitrogen bases

question

In DNA what nitrogen base always pairs with Adenine?

answer

Thymine

question

In DNA what nitrogen base always pairs with Cytosine?

answer

Guanine

question

In DNA what is the name for three successive bases on a DNA strand?

answer

triplet

question

Where does DNA replication take place?

answer

in the nucleus

question

Why does DNA replicate?

answer

- to ensure continuity of hereditary traits

question

What is semi-conservative DNA replication?

answer

- conserves some of the old strand with the new strand

question

Where does DNA unwind?

answer

origin of replication

question

What 2 enzymes cause the DNA to separate?

answer

helicase
DNA nuclease

question

How do helicase and DNA nuclease separate the DNA strands?

answer

they break the hydrogen bonds

question

In DNA replication what is the exposed strand called?

answer

template strand

question

In DNA replication what enzyme joins the new nucleotides to the template strand?

answer

DNA polymerase

question

In DNA replication what is formed when the new nucleotides join with the template strand?

answer

complimentary strand

question

What enzyme connects the new segments of DNA?

answer

Ligase

question

What is RNA

answer

single strand polymer of nucleotides

question

What are the 3 structures of RNA?

answer

phosphate
5 carbon sugar (ribose)
nitrogen base

question

What are the 4 possible nitrogen bases for RNA?

answer

Adenine
Cytosine
Guanine
Uracil

question

What are the 3 differences between DNA and RNA?

answer

different sugars
DNA double strand/RNA single strand
DNA = thymine / RNA = uracil

question

What are the 3 types of RNA involved in protein synthesis?

answer

messenger RNA (mRNA)
transfer RNA (tRNA)
ribosomal RNA (rRNA)

question

what is the function of mRNA?

answer

carries code from DNA to ribosomes

question

what is the function of tRNA?

answer

carries amino acids to mRNA at ribosomes

question

what is the function of rRNA?

answer

responsible for peptide bond

question

What is the name for 3 successive bases on mRNA

answer

codon

question

What is the name for 3 successive bases on tRNA

answer

anticodon

question

What happens in RNA transcription?

answer

DNA information into a molecule of RNA

question

What happens in RNA translation?

answer

RNA to protein (or polypeptite chain)

question

Where does RNA translation occur?

answer

in the cytoplasm/ribosome

question

Where does the RNA strand go after transcription?

answer

out into the cytoplasm

question

What are the 3 main steps of RNA translation?

answer

initiation
polypeptide formation (elongation)
termination

question

In the initiation of RNA translation, what does mRNA attach to?

answer

ribosomal subunit

question

in the initiation of RNA translation, what does tRNA attach to?

answer

codon of mRNA

question

In RNA elongation, a polypeptide bond is formed between what?

answer

two amino acids

question

What causes the termination of RNA translation?

answer

stop codon

question

What do ribosomes use to translate bases into amino acids?

answer

use tRNA to attach to mRNA

question

What is a DNA mutation?

answer

a heritable change in the DNA

question

what does heritable mean (in terms of DNA mutations)?

answer

it can move from one line (generation) of cells to the next line of cells

question

What are 3 common causes of DNA mutations?

answer

radiation
viruses mutagenic chemicals

question

T or F
The information from mutated DNA is NOT likely to be passed on to RNA

answer

0

question

what are the 2 major types of DNA mutation?

answer

point mutations
frameshift mutations

question

what is a point mutation?

answer

a substitution of a base

question

what is a frameshift mutation?

answer

a deletion or insertion of a base

question

what is a silent mutation?

answer

when a change would not affect the amino acid produced

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