genetics midterm 1

____ has a hydroxyl group at the 2 prime carbon position while ___ does not

rna

dna

uracil is found in ___ while thymine is found in ___

rna

dna

rna has an extra functional group on its sugar. having this does not make it more…

volatile

versatile

variable

stable

stable

place the following in order:

• open reading frame

• enhancer/silencer (2)

• core promoter

• 5’ UTR

• start condon

• 3’ UTR

• stop codon

• proximal promoter

1. enhancer/silencer

2. proximal promoter

3. core promoter

4. 5’ UTR

5. start codon

6. open reading frame

7. stop codon

8. 3’ UTR

9. enhancer/silencer

the ___ must remain standard in sequence and position

core promoter

u find a cell in which 10 nucleotides in the core promoter are missing for gene x. what would happen?

nothing

protein will be functionally different

there will be more mRNA

there will be less or no mRNA

there will be less or no mRNA

during ___ enhancers bind to transcription factors and communicate with general transcription factors on the promoter via mediator proteins to dictate how much transcription will occur

initiation

during ____ rna polymerase builds the mrna stand

elongation

the following terms refer to ___

sense strand

coding strand

non-template strand

plus strand

the DNA strand that is not being copied into mRNA

the following terms refer to ___

anti- sense strand

non-coding strand

template strand

minus strand

the DNA strand that is being copied into mRNA

during ____ NusA or Rho bind to the mRNA stand being produced and physically block RNA polymerase from continuing to copy DNA

termination

during ____ in eukaryotes: introns are cut out, a 5’ guanine cap is added, and a 3’ poly-A tail is added

mRNA processing

mRNA processing is required to…

label the mRNA so it is identifiable

prevent the mRNA from getting broken down by the cell

amino acids gain their unique chemical identity from their ___ and there are ___ different variations of them

r group
20

name the nonpolar and hydrophobic amino acids

alanine

valine

leucine

isoleucine

methionine

proline

tryptophan

phenylalanine

nonpolar and hydrophobic amino acids are characterized by

hydrocarbon side chains with nonpolar covalent bonds

nonpolar and hydrophobic amino acids are found primarily on the ___ of a protein

inside

polar and hydrophilic amino acids are found primarily found on the ___ of a protein

outside

name the polar and hydrophilic amino acids

glycine

serine

threonine

cysteine

tyrosine

aspargine

glutamine

polar and hydrophilic amino acids are characterized by

having oxygens, nitrogens, or sulfur resulting in an unequal share of charge in its covalent bonds

name the polar, positively charged/basic amino acids

histidine

lysine

arginine

name the polar, negatively charged/acidic amino acids

aspartic acid

glutamic acid

the general structure of an amino acid includes ___ (3)

amino group

carboxyl group

r group

primary structure

linear order of amino acids

secondary/tertiary structure

folded protein

quaternary structure

multiple proteins linked together

a protein’s function is based on its ___ (2)

shape and charge

___ amino acid = ___ RNA neucleotides = __ codons

1 amino acid = 3 RNA neucleotides = 1 codon

how does the cell know when the coding sequence on the mRNA starts or ends?

there are special codons that indicate when translation should start and stop

AUG or methionine is the ___ and codes for an ___. It may ___ many times within an open reading frame

start codon

amino acid

repeat

UAA, UGA, UAG are all ____ but DO NOT code for an ___. It only appears ___ at the end of an open reading frame

stop codons

amino acid

one time

when reading mRNA always start from the ___ end

5’

initiation phase of translation

mRNA is bound to the small ribosomal subunit

the initiator tRNA hydrogen bonds to start codon of the mRNA

via an anticodon

elongation phase of translation

tRNA binds to the mRNA via anticodons

building a polypeptide chain

going from the A —> P —> E sections of the ribosome (right to left)

termination phase of traslation

a special protein recognizes the stop codon on the mRNA and stops translation

the ribosome breaks apart to go and find another strand of mRNA

eukaryotes: transcription is in ___ and translation is in the ___

nucleus

cytoplasm

prokaryotes: transcription and translation is in the ___

cytoplasm

prokaryotic gene regulation

• change mRNA life span

• change translation rate

• change protein activity by chemical mods

• genes clustered into operons

eukaryotic gene regulation

• chromatin remodeling

• control elements (proximal/core promoter, enhancer/silencer, UTRs) + transcription factors

• mRNA alternative splicing

• mRNA degredation

anabolic

build up

catabolic

break down

Trp operon in prokaryotes is regulated by

repressors activated by their corepressor (Trp)

the repressor binds to the operator and blocks RNA polymerase

Lac operon in prokaryotes is regulated by

repressors deactivated by their inducer (allolactose)

the repressor detaches from the operator allowing RNA polymerase to copy the gene

The Trp operon in prokaryotes is a ____ operon, it is ___ by default

repressible

on

The Lac operon in prokaryotes is an ____ operon, it is ___ by default

inducible

off

Repressible genes are usually ____

anabolic

Inducible genes are usually ____

catabolic

point mutation

change in one nucleotide

silent mutation

change in nucleotide sequence that does not change the amino acid specified by a codon

no change in phenotype

missense mutation

change in nucleotide sequence that changes the amino acid specified by codon

change in primary structure of protein

nonsense mutation

change in nucleotide sequence that results in an early stop codon

leads to mRNA breakdown or shortened polypeptide

frameshift

addition or deletion of a nucleotide

alter meaning of all subsequent codons

gain of function/dominant mutation

still have protein product

change in function or amount

loss of function/recessive mutation

less protein

broken protein

no transcription/translation

genetics

the study of heredity and the variation of inherited characteristics in populations

evolution

a change in the genetic composition of a population over time

genetic composition changes when the frequency of gene variants/alleles change

allele

variant of a gene

population

localized group of individuals capable of interbreeding and producing fertile offspring

gene pool

all the alleles for all loci in a population

(evolution occurs when it changes)

locus/loci

location on the genome somewhere

3 reuirements of evolution of a trait

variation in a trait exists within population

trait is heritable

not all alleles are equally passed to the next generation

individuals better suited for their current environment tend to ___ and their traits ___. Aka they have ___ fitness

have more offspring

become more common in the gene pool

higher

natural selection: acts on ___ but its consequences are measured in ___

individuals

populations

natural selection: acts on ___ but only ___ is heritable

phenotype

dna

natural selection: can only act on variation ___ in a population

available

natural selection: is not ___

forward thinking or progressive

natural selection’s effect

can increase or decrease the fitness of an individual

can decrease the # of alleles in a population

mutation’s effect

can increase, decrease, or do nothing to fitness of an individual

increases the # of alleles in a populationthe

asexual reproduction

offspring are identical to the original cell or organism

involves inheritance of all genes from one parent

leads to higher fitness

sexual reproduction

offspring are similar to parents, but show variations in traits

involves inheritance of unique sets of genes from two parents

leads to more variation

binary fission

prokaryotic reproduction involving dividing in half

before a new cell begins mitosis and divides into two cells it must undergo ____

growth and development

interphase

cytoplasmic contents doubled

chromosomes in nucleus duplicate during S phase

if a cell is not going to proceed to mitosis, where in interphase do you think it should stop?

G1

Cells that do not divide will remain in the __ phase

G0

prophase

chromsome condensing

chromosomes contain two sister chromatids

early mitotic spindles

prometaphase

no nucleus

full spindle microtubules

metaphase

chromosomes lined up in the center of cell

anaphase

daughter chromosomes split

telophase and cytokenesis

cells divide

nucleus forming

during what part of the cell cycle would you see chromatids?

M

mitosis

during what phase does the chromosome split?

anaphase

factors that control cell division

presence of nutrients

growth factors

G1/S checkpoint

cell monitors size and DNA integrity

S checkpoint

check for mutations

G2/M

cell monitors DNA synthesis and damage

M checkpoint

cell monitors spindle formation and attachment to kinetochores

When might a frameshift or nonsense mutation not result in a completely defective protein?

A. When a frameshift is balanced out by a nonsense mutation

B. When the mutation occurs in one of the first codons

C. When the mutation occurs in one of the very last codons

D. When the mutation occurs in an exon region

C

Which enzyme is responsible for adding complementary DNA bases to an exposed DNA strand?

A. DNA peptidase

B. DNA polymerase

C. DNA ligase

D. DNA helicase

B

Evolution can be best defined as _____.

A. the production of new species

B. not involving humans

C. always taking a very long time to occur

D. change in allele frequency in a population

D

What is the smallest unit that can evolve?

A. The individual

B. The community

C. The population

D. The cell

C

Scientists isolate cells in various phases of the cell cycle. They find a group of cells that have 11⁄2 times more DNA than G1-phase cells. The cells of this group are _____.

A. between the G1 and S phases in the cell cycle

B. in the S phase of the cell cycle

C. in the M phase of the cell cycle

Page 1

D. in the G2 phase of the cell cycle

B

Question 7

During which phase of mitosis do the chromatids become chromosomes?

A. telophase

B. cytokinesis

C. metaphase

D. prophase

E. anaphase

E

Regulatory proteins that prevent a cell from entering the S phase under conditions of DNA damage are also known as _____.

A. cyclin-dependent kinases

B. cyclins

C. antibodies

D. tumor suppressors

D

Independent assortment of chromosomes occurs during _____.

A. mitosis and meiosis I

B. mitosis only

C. meiosis I only

D. mitosis and meiosis II

E. meiosis II only

C

Crossing over normally takes place during which of the following processes?

A. mitosis

B. meiosis II

C. meiosis I

D. mitosis and meiosis II

C

If a cell has completed meiosis I and is just beginning meiosis II, which of the following is an appropriate description of its contents?

A. It has half the amount of DNA as the cell that began meiosis.

B. It has the same number of chromosomes, but each of them has different alleles than another cell from the same meiosis.

C. It has half the chromosomes but twice the DNA of the originating cell.

D. It is identical in content to another cell formed from the same meiosis I event.

E. It has one-fourth the DNA and one-half the chromosomes as the originating cell

A

After telophase I of meiosis, the chromosomal makeup of each new cell is _____.

A. haploid, and the chromosomes are each composed of two chromatids

B. tetraploid, and the chromosomes are each composed of two chromatids

C. diploid, and the chromosomes are each composed of two chromatids

D. diploid, and the chromosomes are each composed of a single chromatid

E. haploid, and the chromosomes are each composed of a single chromatid

A

How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I? They have _____.

A. the same number of chromosomes and half the amount of DNA

B. half the number of chromosomes and half the amount of DNA

C. half the number of chromosomes and one-fourth the amount of DNA

D. twice the amount of cytoplasm and half the amount of DNA

E. half the amount of cytoplasm and twice the amount of DNA

C

Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine. This arrangement _____.

A. determines the tertiary structure of a DNA molecule

B. allows variable width of the double helix

C. permits complementary base pairing

D. determines the type of protein produced

C