Dr. Pfau's Final for Genetics

3'-TACGGTAA-5'

Which of the following DNA molecules is identical to this one?

5'-AATGGCAT-3'

3'-AATGGCAT-5'

3'-TACGGTAA-5'

5'-TTACCGTA-3'

5'-TACGGTAA-3'

5'-CCCGATCCC-3'

Which of the following DNA molecules would bond (complementary) with the one shown here:

5'-GGGATCGGG-3'

5'-CCCGATCCC-3'

5'-CCCGATCCC-3'

5'-GGGATCGGG-3'

3'-TTTGCATTT-5'

17

How many hydrogen bonds hold these two DNA strands together?

5'-GAATTAAA-3'

3'-CTTAATTT-5'

covalent bonds between sugar and phosphate

What holds deoxyribonucleotides together to form a single-stranded DNA molecule?

D

At the OH

f a second deoxyribonucleotide joined with this one, forming a chain of deoxyribonucleotides, at which location would the phosphate of the second deoxyribonucleotide form a bond with the deoxyribonucleotide shown here?

1. Replication: it is needed to produce offspring; not 100% perfect; errors occur

2. Information Content

3. Ability to Change: allows evolution and survival; enables adaption.

What are the three roles of DNA?

DNA is held together by hydrogen bonds. DNA is composed of atoms (Carbon, hydrogen, oxygen, nitrogen, and phosphorus).

How is DNA a molecule?

A phosphate group, a deoxyribose sugar, and a nitrogen base

What does DNA consist of?

5' to 3'

DNA has a directionality of.....

phosphodiester bonds

what kind of bonds form the backbone of DNA

thymine and cytosine

what are the pyrimidines

Adenine and guanine

what are the purines

cytosine

(base pair bonds are the only hydrogen bonds all the other ones are covalent)

guanine bonds with.....

by base pairs

How is DNA measured?

adenine

(base pair bonds are the only hydrogen bonds all the other ones are covalent)

thymine bonds with.....

they can be complementary or antiparallel

what relationships are there between DNA strands?

base pairs

what do the hydrogen bonds between bases form?

DNA is faithfully replicated because each strand is a template for new strands

Why is DNA faithfully replicated?

Complementary base pairing and recognition of specific sequences by proteins.

what are key elements of DNA and RNA function?

True

Sister chromatids are formed when the DNA of a chromosome replicates.

True or False

False

The centromere is always in the middle of a chromosome.

True or False

the centromere

Kinetochores are attached to.....

False

Non-homologous chromosomes contain different versions of the same genes.

True or False

True

Sex chromosome pairs look different in one of the sexes whereas autosomal chromosome pairs look the same in both sexes.

True or false

eight

This cell contains 4 non-replicated chromosomes. How many replicated chromosomes would it contain immediately following DNA replication?

Each member of the pair originated from the parents whose haploid cells fused to create this cell

This cell contains homologous pairs of chromosomes (two pairs are illustrated). From where did each member of the pair originate?

chromosomes

Which of the following entities can be homologous? (note: you may chose more than one response)

people

chromosomes

genes

cells

A

In the diagram below, which represents two different alleles of the same gene: A, B, or C?

True

Cell #1 is homozygous for genes R and B, and cell #2 is homozygous for gene Q but heterozygous for gene T.

true or false

R/r;B/b

What is the correct genotype for this cell? [Note: a backslash indicates genes or alleles on homologous chromosomes whereas semicolon indicates genes on non-homologous chromosomes.]

R/r;B/b

RB;rb

R;B/r;b

RB/rb

False

The genotype for this cell is TQ/Tq. [Note: a backslash indicates genes or alleles on homologous chromosomes whereas a semicolon indicates genes on non-homologous chromosomes.]

True or False

a cell

a person

Which of the following entities can be diploid? (there may be more than one correct answer)

a cell

a person

a chromosome

a gene

an allele

a cat

a cell

Which of the following entities can be homozygous? (there may be more than one correct answer)

a cat

a cell

a chromosome

a gene

an allele

A gene is a stretch (length or region) of DNA

A gene is DNA but not all DNA is a gene; genes contain information needed to produce a RNA molecule, which may or may not be used to produce a polypeptide; which may or may not by itself be a protein.

what are the two definitions of a gene?

Promoter

Transcribed region

Termination Sequence

what are the three functional regions of a gene?

during metaphase of mitosis

When is chromosome morphology usually visualized?

the replication of chromosomes and chromatids.

chromosome morphology involves the.....

a unique DNA sequence; all DNA have a centromere sequence

what is a centromere?

the centromere is in the middle

what is a metacentric centromere?

the centromere is almost in the middle

what is a submetacentric centromere?

The centromere is close to the top

what is a acrocentric centromere?

The centromere is at the top making it telocentric.

what is a telocentric centromere?

the kinetochore causes chromosome motion by moving itself away by spindle fibers

what is the kinetochore?

unique DNA sequences on all the ends of chromosomes to help keep them from unraveling.

What are telomere?

it is a human constructed diagram that organizes chromosomes from largest to smallest except for x and y chromosomes.

what is a karyotype?

Chromosomes that look the same

what are homologous chromosomes

Non homologous chromosomes are chromosomes that differ in size, shape, or DNA sequence

what are non homologous chromosomes

Females have two x chromosomes (XX)

Males have one X and one y chromosomes (XY)

what is the difference between the sex chromosomes?

genes determine the sex of an organism not the sex chromosomes.

Sex chromosomes are the chromosomes that differ between the sexes.

what determines the sex of an organism?

A Locus or loci is a location of a gene on a chromosome

What is a locus or loci?

ONE of any number of DNA sequence variations at a particular locus.

what is an allele?

mutations

what creates new alleles?

Single Nucleotide Polymorphism

(Alleles that differ by one letter)

What are SNPs?

indels are alleles that differ in length

what are indels?

genotypes are combination of alleles on homologous pairs

what are genotypes?

two sets of chromosomes.

how many sets of chromosomes does a diploid cell have

one set of chromosomes

how many sets of chromosomes do haploid cells have?

Polyploid is the condition of having more than two sets of chromosomes

what is polyploid?

A genome is made of stretches of DNA from different sources

what is a genome?

to the right of it

In this particular diagram of transcription, where is the promoter sequence located relative to the transcription bubble?

aspartic acid

What will be the 6th amino acid in the polypeptide encoded by this mRNA molecule?

glycine

aspartic acid

Methionine

GAU

CTA

B, D, and E

Where in this cell would transcription occur?

DNA

What serves as the template during transcription?

True

The start codon serves as the signal to initiate translation.

True or False

from 5' to 3'

In which direction does the ribosome "read" mRNA during translation?

DNA undergoes transcription and RNA forms

Describe transcription

transcription occurs where ever there is DNA

Where does transcription occur?

RNA is single stranded, it contains sugar (ribose), it has two OH groups, contains uracil (U bonds with A), less stable

DNA is double stranded, it contains sugar (deoxyribose), it has one OH group, contains thymine (T bonds with A), more stable

what are the properties of RNA and how do they compare to DNA

DNA template and catalyst

DNA polymerases are RNA that split genes (unzip) can add nucleotides and rezip.

what are the components of transcription?

the DNA strand on the promoter CLOSEST TO 3'

For transcription:

Polymerase will only attach to one strand, it connects to the .......

DNA polymerase reads DNA from 3' to 5'

During transcription, how does DNA polymerase read the DNA?

Initiation:

RNA polymerase binds promoter sequence, transcription bubble forms, and the template strand will be determined.

Elongation:

RNA nucleotides are added, growth occurs 5' to 3', relationship between RNA and gene

Termination:

termination sequence signals protein factors and RNA polymerase released

What is a detailed process of transcription?

ribosomes

where does translation occur?

they are 20 common amino acids that are the code during translation.

The consist of a carboxyl group, an amino group, and an R-group

what are polypeptides and what are their structure?

they link together with covalent bonds (peptides)

how do polypeptides link?

carboxyl group to amino group

what is the directionality of polypeptides?

mRNA contains information to be translated.

what role does mRNA play in translation?

A codon specifies an amino acid during translation. There are 61 codons with 3 termination codons.

What is a codon?

it is redundant because there are 20 amino acids and 64 codons.

Why is the code in translation redundant?

it is almost univeral because it cannot be used on codons of bacteria.

why is the code in translation almost universal?

The structures are hierarchical

primary structure is linear

secondary structure is 3D: Alpha Helix or pleated sheet

tertiary structure is a secondary structure folded onto itself. Many times this is the final form.

Quaternary structure is made of multiple polypeptides.

describe the proteins structures during translation

primary structure

what influences the shape of a protein?

SHAPE

______ determines protein function

only from 3' to 5'

In which direction does RNA polymerase "read" the template strand of a gene?

only from 5' to 3'

In which direction does RNA polymerase "construct" the new RNA molecule?

only strand B

Given this diagram of the partial sequence of a gene with arrows showing the direction of transcription, determine which strand (A or B or both) will serve as the template strand of the gene.

strand A

Gene 1

Strand A

Gene 2

strand B

Gene 3

repressor

what decreases transcription?

Activator

what increases transcription?

transcription increases

when repressors are released from gene regulatory regions, what is the effect?

off

Understanding the effects of gene regulation requires an understanding of a chain of cause and effect: the role of each component, how each interacts, and what the end result will be given a certain set of conditions. Consider five components of an interacting series: a mouse, a cat, a dog, a human, and a light. A squeaking mouse causes a cat to give chase. A running cat causes a dog to bark. A barking dog causes the owner to turn on the lights. If the mouse is silent, will the lights be on or off?

Transcribed

Glucocorticoid is a steroid hormone that binds to an activator that regulates genes involved in development, metabolism, and immune response. In the absence of glucocorticoid, the protein Hsp90 binds to the activator instead, rendering the activator non-functional. The presence of glucocorticoid causes Hsp90 to release from the activator.

Will the genes regulated by this system be transcribed or not transcribed in the presence of glucocorticoid?

the lac operon will be on, and transcription will occur at a maximum rate

In class, I explained that the lac operon is regulated by a repressor that, in turn, was regulated by an effector molecule (lactose). I also alluded to the fact that this was an oversimplification. The lac operon is also regulated by an activator called CAP (or CRP). The repressor and the activator function together to regulate lac operon expression. CAP is induced by cAMP. When there is a lot of glucose in the cell, the level of cAMP drops, which causes CAP to become inactive. Low glucose levels do the reverse, causing CAP to become active.

Which of the following best describes what will happen when lactose is present but glucose is absent in the bacteria's environment?

block the function of repressor proteins

Pathogen response (PR) proteins are produced by plants to defend themselves against pathogens. In the absence of pathogens, repressors block the production of PR proteins. Genes encoding PR proteins are regulated indirectly by ethylene, which is released in response to pathogen attack. Receptor molecules on the endoplasmic reticulum bind ethylene and cause the repressors to be nonfunctional.

If you wanted to artifically increase the production of PR molecules, which of the following might work?

HSP genes will not be transcribed, causing the organism to be susceptible to heat stress.

Heat shock proteins (HSPs) help organisms survive heat stress. Genes that encode heat shock proteins are regulated by activators (called HSP transcription factors) which bind regulatory regions of HSP genes only when temperatures are high.What would the result be of a mutation in the gene encoding HSP transcription factors rendering them nonfunctional?

Regulation determines the different genes being translated in different cells. For example: liver proteins are different than brain proteins.

Also, different genes need to be expressed at different times and at different amounts. Regulation accounts for differences among cells in different environments and different tissues. Regulation occurs in response to external stimuli.

why must genes be regulated?

A wildtype is used to describe the typical trait/most common allele.

what is a wildtype?

mutant is used to describe the new trait/abnormal allele. Mutant traits can either become less common or become the wildtype.

what is a mutant?