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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
What stain is used to see banding pattern of chromosomes under light microscopy?
Giemsa stain
26
Cytogenetic technique: Karyotyping
using light microscopy to see and organize chromosomes based on their size and banding pattens
27
Cytogenetic technique: Whole Chromosome Painting
organizing chromosomes based on color of whole chromosome
28
What is found on chromosomes?
- genes (encoding proteins and RNA molecules) | - interdispersed DNA that does not contain genes
29
What is interspersed DNA that does not contain genes?
- regulatory information | - Junk DNA
30
What year was the first draft of the Human Genome Project completed?
2001
31
What year was the first Human Genome Project sequence published?
2004
32
What % of the gene is comprised of coding region (mostly intronic sequence)?
5%
33
Genome characteristics
- Little protein coding regions - DNA is from transposable elements - Lots of intronic sequences - Regulatory sequences
34
How many base pairs are coding regions (exons) floating in a sea of large introns?
145 bp
35
Which sequences are relatively conserved during evolution?
functional sequences
36
Which sequences mutate randomly without consequence?
Non-functional sequences
37
Comparisons of human genome with other animals
-roughly 5% consists of multi species conserved sequences
38
About how much of the conserved sequences codes for proteins?
1/3
39
Conserved sequences have some _______ (not translated into protein) and some sequences have __________ functions.
- some RNA | - regulatory functions
40
What is conserved synteny?
- sharing of same genes | - large blocks of genes conserved in the same order on the chromosome
41
What happens during interphase?
- chromosomes replicated - chromosomes decondensed - chromosomes can't be easily distinguished
42
What happens during mitosis?
- chromosomes become highly condensed | - chromosomes separated into 2 daughter nuclei
43
What are 3 chromosome requirements that must be passed on to each daughter cell at division?
- DNA replication origin - Centromere - Telomeres
44
What is the DNA replication origin?
where duplication of the DNA begins
45
What is a centromere?
Allows one copy of each duplicated and condensed chromosome to be pulled into each daughter cell when the cell divides
46
What are telomeres?
- at ends of chromosomes - contain repetitive sequences - enable ends to be efficiently replicated
47
How many times are Mitotic chromosomes condensed compared to interphase DNA?
500 times
48
What is a dynamic situation?
allows rapid localized access to DNA for gene expression
49
What do DNA binding proteins do?
- involved in forming chromosomes | - are histones and non-histone chromosomal proteins
50
Protein + nuclear DNA = ?
chromatin
51
What is the most basic unit of chromosome packing?
nucleosome
52
Chromatin isolated directly from interphase nucleus forms _________.
30nm thick thread
53
If the chromatin thread is partially unfolded, what does it form?
"beads on a string" ``` String = DNA Beads = DNA wound around histones ```
54
What do nucleases do to nucleosomes?
- break down DNA by cutting between nucleosomes | - degrade exposed DNA between nucleosome core particles (linker DNA)
55
What is linker DNA?
- DNA between nucleosome core particles | - can be few-80nt
56
How many histone proteins does each individual nucleosome core particle consist of?
8 histone proteins = histone octomer
57
What makes up a histone octomer?
(2) H2A (2) H2B (2) H3 (2) H4 Double stranded DNA that is 147 nucleotide pairs long
58
How often do nucleosomes repeat?
every 200 nucleotide pairs or so
59
What are histones?
- small proteins | - common structural motif = histone fold
60
Characteristics of high resolution structure of nucleosome core particle
- disc shaped - DNA wrapped every 1.7 turns - N terminal amino acid tail that extends out from the core
61
What are the N terminal amino acid tails on the nucelosome core particle subject to?
covalent modifications important for chromatin regulation "handshake" interaction
62
How is DNA packaged?
interactions between DNA and histones
63
How many Hydrogen bonds are formed between DNA and the histone core in each nucleosome?
142 hydrogen bonds
64
Are the interactions between DNA and histones hydrophobic or hydrophilic?
hydrophobic
65
What are salt linkages?
- lysine and arginine (+ charges) comprise more than 1/5 of histone residues - effectively neutralize (-) charged DNA backbone
66
Histones are highly ______, most changes would be lethal
conserved
67
Where are the 2 differences between pea and cow histones?
H4
68
What do specialized varient histone proteins do?
add to various possible chromatin structures
69
What is in a constant state of flux?
nucleosomes
70
DNA is unwrapped in the nucleosome ________ times per second.
4 times per second
71
DNA remains unwrapped for _________ milliseconds before tightening up again.
10-15 miliseconds
72
What do chromatin remodeling complexes allow?
Allow further loosening of DNA/histone contact
73
Proteins are related to helices and are ATP ________; bind to both protein core and DNA
dependent
74
Chromatin remodeling changes ____________ making DNA less tightly bound
structure of nucelosome temporarily
75
Repeated cycles ________ nucleosome sliding, making DNA available to other proteins in the cell
catalyzes
76
What is the diameter of the dense fibrous structure of a nucleosome?
30 nm
77
What is the zig-zag model of nucleosome packing?
- histone tails might facilitate stacking (H4) | - H1 (linker histone) is present in 1:1 ratio with nucleosome cores
78
What is Histone H1?
- 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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