genetics test 4 study guide

Question 1

Mismatch repair function

Answer 1

Fixes replication errors that escape proofreading.

Question 2

How mismatch repair distinguishes strands

Answer 2

Old strand = methylated; new strand = not methylated.

Question 3

Direct repair definition

Answer 3

Restores nucleotide structure without replacing bases.

Question 4

Base-excision repair

Answer 4

DNA glycosylase removes damaged base → AP site → polymerase fills gap.

Question 5

Nucleotide-excision repair

Answer 5

Cuts DNA on both sides of bulky lesion; removes entire segment.

Question 6

Double-strand break repairs

Answer 6

HDR = accurate; NHEJ = error-prone.

Question 7

Disease example from NER defect

Answer 7

Xeroderma pigmentosum.

Question 8

Restriction enzyme purpose

Answer 8

Cuts DNA at specific sequences.

Question 9

Sticky vs blunt ends

Answer 9

Sticky: overhangs.
Blunt: straight cuts.

Question 10

Role of ligase in cloning

Answer 10

Seals sugar-phosphate backbone.

Question 11

Gel electrophoresis principle

Answer 11

DNA separates by size (small = farther).

Question 12

Southern blot detects

Answer 12

DNA

Question 13

Northern blot detects

Answer 13

RNA

Question 14

Western blot detects

Answer 14

Protein

Question 15

Essential features of a plasmid vector

Answer 15

ORI + selectable marker + restriction sites.

Question 16

Selectable marker function

Answer 16

Identifies cells that took up plasmid (ex: amp^R).

Question 17

Blue-white screening purpose

Answer 17

White colonies = successful insertion (lacZ disrupted).

Question 18

Expression vector requirement

Answer 18

Promoter + RBS for transcription/translation.

Question 19

BAC size capacity

Answer 19

Up to 300 kb.

Question 20

Ti plasmid use

Answer 20

Transfers genes into plants.

Question 21

PCR steps

Answer 21

Denature → Anneal → Extend.

Question 22

Taq polymerase role

Answer 22

Heat-stable DNA polymerase used in PCR.

Question 23

Each PCR cycle effect

Answer 23

DNA amount doubles.

Question 24

Sanger sequencing key idea

Answer 24

Uses ddNTPs to terminate extension.

Question 25

Illumina sequencing feature

Answer 25

Massively parallel short reads.

Question 26

PacBio feature

Answer 26

Very long reads, single-molecule sequencing.

Question 27

Nanopore feature

Answer 27

Reads DNA as it passes through pore → electrical signal.

Question 28

STR definition

Answer 28

Short tandem repeats used for identification.

Question 29

STR genotype interpretation

Answer 29

One peak = homozygous two peaks = heterozygous.

Question 30

CRISPR-Cas9 function

Answer 30

Creates targeted double-strand break.

Question 31

Guide RNA purpose

Answer 31

Directs Cas9 to matching DNA sequence.

Question 32

Prime editing

Answer 32

Replaces specific DNA sequences without DSBs.

Question 33

CRISPR limitation

Answer 33

Off-target cleavage.

Question 34

Transcriptome definition

Answer 34

All RNA molecules in a cell.

Question 34

Proteome definition

Answer 34

All proteins encoded by genome.

Question 35

Microarray purpose

Answer 35

Compares gene expression.

Question 36

RNA-seq purpose

Answer 36

Sequencing all RNA transcripts.

Question 37

Reporter gene example

Answer 37

GFP.

Question 38

Orthologs

Answer 38

Same gene in different species.

Question 39

Paralogs

Answer 39

Gene duplicates within a species.

Question 40

Horizontal gene transfer

Answer 40

Gene movement across species.

Question 41

Segmental duplication

Answer 41

Large duplicated genomic blocks.

Question 42

Collinearity

Answer 42

Gene order conserved between species.

Question 43

2D-PAGE separates proteins by

Answer 43

Charge → then size.

Question 44

Mass spectrometry use

Answer 44

Identifies proteins by mass-to-charge ratio.

Question 45

Protein microarrays

Answer 45

Test protein–protein interactions.

Question 46

AAV vector advantages

Answer 46

Low immune response; infects many cells.

Question 47

Lentivirus use

Answer 47

Stable integration → used for ex vivo therapy.