DNA and Genes

Question 0

Epigenetics

Answer 0

Interaction of many genes or of the genotype with the environment.

Question 1

3 genetic rules

Answer 1

1. Genotype and phenotype are distinct
2. Phenotype a from some alleles can mask others
3. Organisms have two copies of each gene.

Question 2

Replicon

Answer 2

Length of DNA that is replicated following one initiation event at a single origin.

Question 3

What removes primers and fills in gaps

Answer 3

DNA polymerase ll

Question 4

Critical requirements for replication

Answer 4

Template
Primer
3’OH end

Question 5

What synthesizes RNA primer

Answer 5

Primase

Question 6

Enzymes needed at replication fork

Answer 6

DNA polymerase lll
SSBP
DNA gyrase
DNA helicase
Primase

Question 7

Why deoxyribose sugar in DNA?

Answer 7

Additional OH affect helix structure/packing

DNA must remain stable (DNA needed for life, RNA less so)

Question 8

Mutation in splice site causes

Answer 8

Splicing at alternative sites (cryptic sites)

Question 9

Point of genetic exchange between synapses chromosomes

Answer 9

Chiasmata

Question 10

Complete linkage

Answer 10

Only parental gametes produced (no crossing over)

Question 11

Degree of crossing over between two loci is proportional to..

Answer 11

Interlocus distance.

Question 12

G rich regions looped back on themselves..

Answer 12

G-quartets.

Question 13

Genotype

Answer 13

The alleles present at one or more specific loci

Question 14

Genome

Answer 14

The total genetic information in an organism

Question 15

Phenotype

Answer 15

The observable characteristics of an organism distinct of its genotype.

Question 16

Pure breeding

Answer 16

When a certain trait is seen regardless of generation.

Question 17

Chromatin

Answer 17

Complex of DNA, histones and nonhistone proteins within nucleus of eukaryotic cell

Question 18

Chromatic

Answer 18

One of the two copies of a replicated chromosome that is joined at the centromere to the other copy

Question 19

Centromere

Answer 19

Chromosomal region that holds sister chromatids together

Question 20

Nucleosome structure

Answer 20

Histones octamer

• 2 copies of each core histone
• long N terminus amino acid tail from each histone

Question 21

Transposon

Answer 21

DNA sequence that can change its position within the genome and alter the genome size

Question 22

Satellite DNA

Answer 22

Large arrays of tandemly repeating, non-coding DNA

- main component of centromeres

Question 23

Why is DNA replication regulated?

Answer 23

• to ensure all chromosomes replicate once per cycle

- to ensure that replication of the genome is error-free

Question 24

Replisome

Answer 24

Replicates DNA bidirectionally from origins

Question 25

Modes of DNA replication

Answer 25

- conservative - semi conservative - dispersive

Question 26

Sequences that enhance ORC recognition

Answer 26

- AT-rich sequences - dinucleotide repeats - asymmetrical purine-pyrimidine sequences - matrix attachment region sequences

Question 27

Topoisomerase

Answer 27

Initiates unwinding by cutting one of the strands

Question 28

Helicase

Answer 28

- assists unwinding

Question 29

SSBP

Answer 29

Stabilizes separated strands and prevents them from recombining

Question 30

DNA polymerase

Answer 30

- links together nucleotides monomers as they hydrogen bond to complementary bases - can check for errors and make corrections

Question 31

Ligase

Answer 31

Unites small unattached DNA segments on a strand

Question 32

Key issues in DNA replication

Answer 32

- unwinding of helix - reducing increased coiling generated during unwinding - synthesis of primer for initiation - discontinuous synthesis of second strand - removal of RNA primers - joining of gap-filling DNA to adjacent strand - proofreading

Question 33

Role of S checkpoint

Answer 33

- stabilizes stalled replication forks - inhibition of initiation at unfired origins - inhibition of entry into G2 or M - slowing of ongoing fork progression

Question 34

Implications for low DNA replication

Answer 34

Wound healing | Development of embryo

Question 35

Functions of telomeres

Answer 35

- protect chromosomes from improper fusion | - protect from degradation

Question 36

How can dsDNA be damaged

Answer 36

- chemicals - spontaneous hydrolysis of nucleosides - spontaneous hydrolysis of cytosine to uracil - oxidation or methylation - UV light

Question 37

Uses of isolated genomic DNA

Answer 37

``` PCR template Cloning DNA sequencing DNA fingerprinting Crime investigation ```