DNA & Gene Expression

Question 1

DNA sequencing

Answer 1

To determine the nucleotide sequence of DNA; can determine relative gene count

Question 2

Southern blot

Answer 2

To detect DNA; can be used to determine relative gene count

Question 3

Northern blot

Answer 3

To detect RNA; can NOT be used to determine relative gene count

Question 4

Double-stranded DNA breaks (DSB)

Answer 4

Between a deoxyribose sugar and a phosphate group

Question 5

Coding strand

Answer 5

Exact same as mRNA except U will be in place of T

Question 6

Topoisomerase

Answer 6

The role is to relieve torsional strain caused by helicase’s unzipping of DNA strands during replication

Question 7

Telomerase

Answer 7

An enzyme that extends telomeres, helping prevent their deterioration during DNA replication

Question 8

Errors with DNA polymerase

Answer 8

These will be either repaired by DNA polymerase itself or other enzymes whose function is to help identify and repair mutations

Question 9

Penetrance

Answer 9

The rate at which, given a particular genotype, that genotype leads to a related phenotype (ie, given that 88% of the population has the gene in question but only 4% of individuals show the phenotype, the gene can be said to have low penetrance)

Question 10

Expressivity

Answer 10

Broad: (ie, a degree of variability in the amount of red pigment produced)
Narrow

Question 11

Adenine to guanine - what will happen following replication?

Answer 11

With treatment, the G-C pair is replaced with A-C pair. However, C does not base pair with A, so after replication, the C will be replaced with T; this then allows A to basepair with T

Question 12

Red hair

Answer 12

Polygenic inheritance in much the same way as green eyes; there are only two alleles at the primary gene locus, but there are secondary alleles at another gene locus that can be unmasked by a homozygous genotype at the first locus

Question 13

Functions of hair

Answer 13

Provide a lever to increase sensation
Trap air to increase heat retention
Provide physical protection

Question 14

Rapid onset of Alzheimer’s in patients with Down’s syndrome, why?

Answer 14

Individuals with Down’s syndrome have three copies of the amyloid precursor protein gene which are transcribed simultaneously

Question 15

mRNA sequence 5’-UGUAAUC-3’ is transcribed from

Answer 15

5’-GATTACA-3’

Question 16

Stabilizing selection

Answer 16

Maintaining a phenotype; the mean remains the same and the distribution narrows

Question 17

Convergent/divergent evolution

Answer 17

Involve the shift of form/function in different environments

Question 18

Disruptive selection

Answer 18

Produce multiple phenotypes

Question 19

Semi-conservative replication

Answer 19

After a single round of replication, one strand would be heavy and one would be light
- Centrifuging would demonstrate it has some intermediate density
- Melting the DNA separates the H-bonds which hold the strands, leaving us with one heavy (old DNA) and one light (new DNA)

Question 20

In vivo, an E. coli (bacteria and prokaryote) cell undergoes DNA replication, the new copy of DNA:

Answer 20

Is attached to a new part of the cell membrane during binary fission

Question 21

Mitosis and meiosis

Answer 21

Unique to eukaryotes

Question 22

Trait is expressed in the children of two unaffected parents, and there is a preponderance of affected male children - what is the inheritance?

Answer 22

X-linked recessive

Question 23

Y-linked dominant

Answer 23

Father-to-son transmission

Question 24

Autosomal recessive

Answer 24

Should have 1:1 male-female ratio

Question 25

Autosomal dominant

Answer 25

Should not show generational skipping

Question 26

Heteroplasmy

Answer 26

The variability in the mitochondrial composition of the cell and is best explained by self-replication of mitochondria

Question 27

Mitochondrial apoptosis pathway includes:

Answer 27

Loss of proton gradient across the inner mitochondrial membrane, release of caspases and cytochrome c, and decrease in Bcl-2 anti-apoptotic protein translation

Question 28

If a mitochondrial disorder produced a non-functional mitochondrial tRNA for lysine

Answer 28

The mitochondrion will not be able to produce proteins

Question 29

Accuracy of DNA synthesis

Answer 29

Is increased when DNA polymerase exhibits 3’ to 5’ exonuclease activity (commonly referred to as proofreading)

Question 30

Gel electrophoresis and DNA sequences

Answer 30

The closer the nucleotide to the positive end, the closer that it is to the 5’ side
Ex: if there are three Ts are the bottom and 2 As at the top it would go: 5’ TTTAA 3’

Question 31

Phosphodiester linkages

Answer 31

Individual nucleotides within the backbone of the regulatory RNAs

Question 32

Disulfide bridges

Answer 32

Are covalent bonds that link cysteine residues within protein; not involved in the linkage of nucleotides within a nucleic acid bone

Question 33

Hydrogen bonds

Answer 33

Hold base-pairing nucleotides together, not nucleotides within a backbone

Question 34

Glycosidic linkages

Answer 34

Bind carbohydrates together

Question 35

Transformation

Answer 35

The process that transfers genetic material from the environment into bacteria

Question 36

Transduction

Answer 36

The process by which nucleic acids are transferred from viruses to cells

Question 37

Contamination

Answer 37

Act of making a solution or sample impure

Question 38

Conjugation

Answer 38

The exchange of nucleic acids between bacteria

Question 39

How many gametes formed from a diploid organism that is heterozygous at three unlinked genes

Answer 39

8 distinct gametes; each gene (A, B, C) will have two alleles (1 and 2)

Question 40

Splicing

Answer 40

First part of the post-transcriptional process: DNA is first transcribed in primary transcript and then modified to become mRNA