test 2 study guide in depth

Question 1

Aneuploidy

Answer 1

Caused by nondisjunction

Question 2

Monosomy

Answer 2

(2n–1)

Question 3

Trisomy

Answer 3

(2n+1)

Question 4

Nullisomy

Answer 4

(2n–2)

Question 5

Tetrasomy

Answer 5

(2n+2)

Question 6

Polyploidy

Answer 6

Autopolyploidy (same species)
Allopolyploidy (hybridization → chromosome doubling)

Question 7

Down syndrome

Answer 7

Trisomy 21

Question 8

edwards

Answer 8

Trisomy 18

Question 9

Patau

Answer 9

Trisomy 13

Question 10

Turner

Answer 10

XO

Question 11

Klinefelter

Answer 11

XXY

Question 12

Deletions

Answer 12

Loss of chromosome segment
Causes pseudodominance

Question 13

Duplications

Answer 13

Unequal crossing over
Dosage imbalance

Question 14

Inversions

Answer 14

Paracentric (does not include centromere)
Pericentric (includes centromere)
Can suppress recombination

Question 15

Translocations

Answer 15

Reciprocal or nonreciprocal
Robertsonian (fusion of acrocentric chromosomes)

Question 16

Consequences of Rearrangements

Answer 16

Abnormal pairing in meiosis
Reduced fertility
Gene dosage effects
Breakpoints can activate/inactivate genes

Question 17

Horizontal Gene Transfer

Answer 17

Transformation
Conjugation
Transduction

Question 18

Transformation

Answer 18

Uptake of naked DNA

Question 19

Conjugation

Answer 19

Requires F plasmid
F+ cell transfers DNA → F– cell

Question 20

Transduction

Answer 20

Bacteriophage carries DNA
Generalized vs Specialized

Question 21

Phage Life Cycles

Answer 21

Lytic cycle
Lysogenic cycle

Question 22

Lytic cycle

Answer 22

Phage replicates, bursts host

Question 23

Lysogenic cycle

Answer 23

Phage integrates as prophage
Can later enter lytic cycle

Question 24

CRISPR-Cas Immune System

Answer 24

Adaptation – acquire spacer

Expression – transcribe crRNA

Interference – Cas cuts matching DNA

Question 25

Phage Mapping

Answer 25

Mixed infections → recombinant plaques Recombination frequency = map distance

Question 26

Retroviruses

Answer 26

Reverse transcriptase Integrates into host genome

Question 27

HIV

Answer 27

Infects helper T cells High mutation rate

Question 28

Influenza

Answer 28

Segmented RNA genome Antigenic shift = reassortment Antigenic drift = mutations

Question 29

Properties of Genetic Material

Answer 29

Stores information Replicates accurately Can mutate Can be expressed

Question 30

Griffith

Answer 30

transformation

Question 31

Avery, MacLeod, McCarty

Answer 31

DNA is transforming principle

Question 32

Hershey–Chase

Answer 32

DNA enters phage-infected cells

Question 33

Chargaff

Answer 33

A=T, G=C

Question 34

DNA Composition

Answer 34

Sugar-phosphate backbone Nitrogenous bases (A,T,G,C) Hydrogen bonding → A–T = 2 H-bonds → G–C = 3 H-bonds

Question 35

DNA Structure Levels (primary)

Answer 35

nucleotide sequence

Question 36

DNA Structure Levels (secondary)

Answer 36

double helix

Question 37

DNA Structure Levels (tertiary)

Answer 37

packing & supercoiling

Question 38

Nucleosome

Answer 38

DNA + histone core

Question 39

30 nm fiber

Answer 39

→ loops → scaffolding

Question 40

RNA Basics

Answer 40

Ribose sugar Uracil instead of thymine Single-stranded Many forms: mRNA, tRNA, rRNA

Question 41

Replication Basics

Answer 41

Semiconservative 5′→3′ synthesis Template read 3′→5′ Requires primer

Question 42

Meselson–Stahl Experiment

Answer 42

Proved semiconservative replication Generation 1: intermediate band Generation 2: light + intermediate

Question 43

Replication Models

Answer 43

Theta replication (bacteria) Rolling circle (viruses, plasmids) Linear eukaryotic (multiple origins)

Question 44

DnaA

Answer 44

initiates replication

Question 45

Helicase

Answer 45

unwinds DNA

Question 46

SSB

Answer 46

prevents reannealing

Question 47

Gyrase (Topoisomerase)

Answer 47

relieves supercoiling

Question 48

Primase

Answer 48

synthesizes RNA primers

Question 49

DNA Pol III

Answer 49

main synthesizing enzyme

Question 50

DNA Pol I

Answer 50

removes primers + fills gaps

Question 51

Ligase

Answer 51

seals nicks

Question 52

What is aneuploidy?

Answer 52

An abnormal number of chromosomes (2n ± 1).

Question 53

What causes aneuploidy?

Answer 53

Nondisjunction in meiosis.

Question 54

What is monosomy?

Answer 54

2n–1.

Question 55

What is trisomy?

Answer 55

2n+1.

Question 56

Example of human trisomy?

Answer 56

Down syndrome (Trisomy 21).

Question 57

Example of monosomy in humans?

Answer 57

turner syndrome (XO)

Question 58

What is Klinefelter syndrome?

Answer 58

XXY

Question 59

Can autosomal monosomy survive?

Answer 59

Usually lethal.

Question 60

What is polyploidy?

Answer 60

extra full sets of chromosomes (3n, 4n).

Question 61

What is autopolyploidy?

Answer 61

Chromosome doubling within one species.

Question 62

What is allopolyploidy?

Answer 62

Hybridization + chromosome doubling from two species.

Question 63

are polyploids common?

Answer 63

Yes, in plants. Rare in animals.

Question 64

What is a chromosome deletion?

Answer 64

Loss of a chromosome segment.

Question 65

What is pseudodominance?

Answer 65

Recessive allele expressed due to deletion of dominant allele.

Question 66

What causes duplications?

Answer 66

Unequal crossing over.

Question 67

Why are duplications harmful?

Answer 67

Gene dosage imbalance.

Question 68

What is an inversion?

Answer 68

Chromosome segment reversed end to end.

Question 69

Paracentric inversion?

Answer 69

Does NOT include the centromere.

Question 70

Pericentric inversion?

Answer 70

Includes the centromere.

Question 71

Key consequence of inversions?

Answer 71

Abnormal gametes → reduced fertility.

Question 72

What is a translocation?

Answer 72

Segment moves to a non-homologous chromosome.

Question 73

Reciprocal translocation?

Answer 73

Exchange between chromosomes.

Question 74

Robertsonian translocation?

Answer 74

Fusion of two acrocentric chromosomes.

Question 75

Major risk of translocation carriers?

Answer 75

Miscarriage or unbalanced gametes.

Question 76

What is transformation?

Answer 76

Uptake of naked DNA from environment.

Question 77

What is conjugation?

Answer 77

DNA transfer through cell-to-cell contact.

Question 78

What plasmid enables conjugation?

Answer 78

F plasmid.

Question 79

What cell donates DNA?

Answer 79

F+ cell.

Question 80

What is transduction?

Answer 80

Bacteriophage transfers DNA between bacteria.

Question 81

Generalized transduction?

Answer 81

Random bacterial genes packaged in phage.

Question 82

Specialized transduction?

Answer 82

Only genes near prophage insertion transferred.

Question 83

Lytic cycle?

Answer 83

Phage replicates → cell bursts.

Question 84

lysogenic cycle?

Answer 84

Phage DNA integrates into host genome.

Question 85

step of CRISPR immunity?

Answer 85

Adaptation (spacer acquisition) crRNA expression interference (Cas cuts matching DNA)

Question 86

What is a retrovirus?

Answer 86

RNA virus with reverse transcriptase.

Question 87

Example of retrovirus?

Answer 87

HIV

Question 88

What is antigenic drift in influenza?

Answer 88

Small mutations.

Question 89

What is antigenic shift?

Answer 89

RNA segment reassortment → pandemics.

Question 90

Griffith’s experiment showed?

Answer 90

Transformation.

Question 91

Avery’s experiment showed?

Answer 91

DNA is transforming principle.

Question 92

Hershey–Chase proved?

Answer 92

DNA, not protein, enters cells.

Question 93

Chargaff’s rules?

Answer 93

A=T, G=C.

Question 94

Nucleotide components?

Answer 94

Sugar + phosphate + base.

Question 95

GC base pairs have how many H-bonds?

Answer 95

3

Question 96

AT base pairs have how many H-bonds?

Answer 96

2

Question 97

DNA strands orientation?

Answer 97

Antiparallel

Question 98

Nucleosome

Answer 98

DNA wrapped around histone core.

Question 99

Euchromatin

Answer 99

active

Question 100

Heterochromatin

Answer 100

condensed/inactive.

Question 101

Which replication model is correct?

Answer 101

Semiconservative

Question 102

Meselson–Stahl first generation outcome?

Answer 102

One intermediate band.

Question 103

Second generation outcome?

Answer 103

Intermediate + light band.

Question 104

Helicase role?

Answer 104

Unwinds DNA.

Question 105

Primase role?

Answer 105

Makes RNA primers.

Question 106

DNA Pol III role?

Answer 106

Main synthesis enzyme.

Question 107

DNA Pol I role?

Answer 107

Removes primers + fills gaps.

Question 108

Ligase role?

Answer 108

Seals nicks

Question 109

Gyrase role?

Answer 109

Relieves supercoiling.

Question 110

Leading strand synthesis?

Answer 110

Continuous

Question 111

Lagging strand synthesis?

Answer 111

Discontinuous (Okazaki fragments).

Question 112

Do eukaryotes have multiple origins?

Answer 112

Yes

Question 113

What is telomerase?

Answer 113

Enzyme that extends telomeres using RNA template.

Question 114

Holliday junction formed during?

Answer 114

Homologous recombination.

Question 115

Junction resolution can produce?

Answer 115

Crossover or non-crossover products.