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MOL BIO Exam #1- Lo > Lec 01- DNA Chromosomes and Genomes 1 > Flashcards

Lec 01- DNA Chromosomes and Genomes 1 Flashcards

1
Q

What are genes?

A

information-containing elements that determine the characteristics of a species

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2
Q

Genes are passed from _____.

A
  • cell to daughter cell

- mostly unchanged

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3
Q

Genes undergo what type of replication?

A

undergoes accurate and unlimited replication

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4
Q

Genes must direct ______

A
  • development of a cell

- daily life of the cell

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5
Q

What do chromosomes contain?

A

DNA and protein

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6
Q

When was it discovered that hereditary information was carried on chromosomes?

A

late 19th century

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7
Q

What makes polynucleotides have polarity?

A

5’ Pi end

3’ OH end

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8
Q

How are nucleotides joined together?

A

by a phosphodiester linkage between 5’ and 3’ carbon atoms

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9
Q

DNA structure

A
  • 2 long polynucleotide chains
  • 4 types of nucleotide subunits
  • 3D structure double helix
  • Antiparallel
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10
Q

What is a nucleotide?

A

5-carbon sugar + nitrogenous base

-Covalently linked via glycosidic bond

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11
Q

Sugar in DNA is ________

A

deoxyribose

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12
Q

What bases are in DNA?

A

A, C, G, T

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13
Q

How many base pairs between each DNA helix turn?

A

10bp per 1 turn

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14
Q

What bases are purines?

A

A and G

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15
Q

What bases are pyrimadines?

A

C and T

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16
Q

Adenine pairs with _______ forming ______ hydrogen bonds.

A

Thymine

2 Hydrogen bonds

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17
Q

Guanine pairs with ________ forming _______ hydrogen bonds.

A

Cytosine

3 Hydrogen bonds

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18
Q

What is a genome?

A

complete set of information in an organism’s DNA

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19
Q

How many nucleotides are in the human genome?

A

3.2x10^9 nucleotides

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20
Q

How many different chromosomes are the nucleotides distributed over the human genome?

A

24 different chromosomes

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21
Q

Each chromosome is a _________ long linear DNA molecule associated with proteins that fold and pack it into compact structure.

A

single

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22
Q

Human cell contains 2 copies of each chromosome except ______ and ______.

A

germ cells and RBCs

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23
Q

How many pairs of autosomes?

A

22 pairs

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24
Q

How many sex chromosomes?

A

2 sex chromosomes

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25
Q

What stain is used to see banding pattern of chromosomes under light microscopy?

A

Giemsa stain

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26
Q

Cytogenetic technique: Karyotyping

A

using light microscopy to see and organize chromosomes based on their size and banding pattens

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27
Q

Cytogenetic technique: Whole Chromosome Painting

A

organizing chromosomes based on color of whole chromosome

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28
Q

What is found on chromosomes?

A
  • genes (encoding proteins and RNA molecules)

- interdispersed DNA that does not contain genes

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29
Q

What is interspersed DNA that does not contain genes?

A
  • regulatory information

- Junk DNA

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30
Q

What year was the first draft of the Human Genome Project completed?

A

2001

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31
Q

What year was the first Human Genome Project sequence published?

A

2004

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32
Q

What % of the gene is comprised of coding region (mostly intronic sequence)?

A

5%

33
Q

Genome characteristics

A
  • Little protein coding regions
  • DNA is from transposable elements
  • Lots of intronic sequences
  • Regulatory sequences
34
Q

How many base pairs are coding regions (exons) floating in a sea of large introns?

A

145 bp

35
Q

Which sequences are relatively conserved during evolution?

A

functional sequences

36
Q

Which sequences mutate randomly without consequence?

A

Non-functional sequences

37
Q

Comparisons of human genome with other animals

A

-roughly 5% consists of multi species conserved sequences

38
Q

About how much of the conserved sequences codes for proteins?

A

1/3

39
Q

Conserved sequences have some _______ (not translated into protein) and some sequences have __________ functions.

A
  • some RNA

- regulatory functions

40
Q

What is conserved synteny?

A
  • sharing of same genes

- large blocks of genes conserved in the same order on the chromosome

41
Q

What happens during interphase?

A
  • chromosomes replicated
  • chromosomes decondensed
  • chromosomes can’t be easily distinguished
42
Q

What happens during mitosis?

A
  • chromosomes become highly condensed

- chromosomes separated into 2 daughter nuclei

43
Q

What are 3 chromosome requirements that must be passed on to each daughter cell at division?

A
  • DNA replication origin
  • Centromere
  • Telomeres
44
Q

What is the DNA replication origin?

A

where duplication of the DNA begins

45
Q

What is a centromere?

A

Allows one copy of each duplicated and condensed chromosome to be pulled into each daughter cell when the cell divides

46
Q

What are telomeres?

A
  • at ends of chromosomes
  • contain repetitive sequences
  • enable ends to be efficiently replicated
47
Q

How many times are Mitotic chromosomes condensed compared to interphase DNA?

A

500 times

48
Q

What is a dynamic situation?

A

allows rapid localized access to DNA for gene expression

49
Q

What do DNA binding proteins do?

A
  • involved in forming chromosomes

- are histones and non-histone chromosomal proteins

50
Q

Protein + nuclear DNA = ?

A

chromatin

51
Q

What is the most basic unit of chromosome packing?

A

nucleosome

52
Q

Chromatin isolated directly from interphase nucleus forms _________.

A

30nm thick thread

53
Q

If the chromatin thread is partially unfolded, what does it form?

A

“beads on a string”

String = DNA
Beads = DNA wound around histones
54
Q

What do nucleases do to nucleosomes?

A
  • break down DNA by cutting between nucleosomes

- degrade exposed DNA between nucleosome core particles (linker DNA)

55
Q

What is linker DNA?

A
  • DNA between nucleosome core particles

- can be few-80nt

56
Q

How many histone proteins does each individual nucleosome core particle consist of?

A

8 histone proteins = histone octomer

57
Q

What makes up a histone octomer?

A

(2) H2A
(2) H2B
(2) H3
(2) H4
Double stranded DNA that is 147 nucleotide pairs long

58
Q

How often do nucleosomes repeat?

A

every 200 nucleotide pairs or so

59
Q

What are histones?

A
  • small proteins

- common structural motif = histone fold

60
Q

Characteristics of high resolution structure of nucleosome core particle

A
  • disc shaped
  • DNA wrapped every 1.7 turns
  • N terminal amino acid tail that extends out from the core
61
Q

What are the N terminal amino acid tails on the nucelosome core particle subject to?

A

covalent modifications important for chromatin regulation

“handshake” interaction

62
Q

How is DNA packaged?

A

interactions between DNA and histones

63
Q

How many Hydrogen bonds are formed between DNA and the histone core in each nucleosome?

A

142 hydrogen bonds

64
Q

Are the interactions between DNA and histones hydrophobic or hydrophilic?

A

hydrophobic

65
Q

What are salt linkages?

A
  • lysine and arginine (+ charges) comprise more than 1/5 of histone residues
  • effectively neutralize (-) charged DNA backbone
66
Q

Histones are highly ______, most changes would be lethal

A

conserved

67
Q

Where are the 2 differences between pea and cow histones?

A

H4

68
Q

What do specialized varient histone proteins do?

A

add to various possible chromatin structures

69
Q

What is in a constant state of flux?

A

nucleosomes

70
Q

DNA is unwrapped in the nucleosome ________ times per second.

A

4 times per second

71
Q

DNA remains unwrapped for _________ milliseconds before tightening up again.

A

10-15 miliseconds

72
Q

What do chromatin remodeling complexes allow?

A

Allow further loosening of DNA/histone contact

73
Q

Proteins are related to helices and are ATP ________; bind to both protein core and DNA

A

dependent

74
Q

Chromatin remodeling changes ____________ making DNA less tightly bound

A

structure of nucelosome temporarily

75
Q

Repeated cycles ________ nucleosome sliding, making DNA available to other proteins in the cell

A

catalyzes

76
Q

What is the diameter of the dense fibrous structure of a nucleosome?

A

30 nm

77
Q

What is the zig-zag model of nucleosome packing?

A
  • histone tails might facilitate stacking (H4)

- H1 (linker histone) is present in 1:1 ratio with nucleosome cores

78
Q

What is Histone H1?

A
  • linker histone
  • larger than other histone proteins
  • less well conserved than other histone proteins
  • contacts both DNA and protein
  • changes path of DNA as it exits the nucelosome

MOL BIO Exam #1- Lo (8 decks)

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