DNA, Chromosomes, and Genomes 1 (lecture 1) Flashcards
1
Q
The information-containing elements that determine the characteristics of a species
A
Genes
2
Q
Genes are passed form cell to daughter cell mostly
A
unchanged
3
Q
Genes undergo accurate and ____ replication
A
unlimited
4
Q
The discovery that hereditary information is carried on chromosomes was made in the late
A
19th century
5
Q
Chromosomes are visible by light microscopy when the cell
A
divides
6
Q
Chromosomes contain ____ and ____ in equal amounts
A
DNA and protein
7
Q
What are the building blocks of DNA
A
Nucleic Acids
8
Q
Polynucleotides have a polarity: ____ phosphoryl end ____ hydroxyl end
A
5’ phosphoric end and 3’ hydroxyl end
9
Q
nucleotides are a 5-carbon sugar and nitrogenous base covalently linked via
A
glycosidic bond
10
Q
what are the nitrogenous bases in DNA
A
- Adenine
- Cytosine
- Guanine
- Thymine
11
Q
DNA has 1 turn every ___ base pairs
A
10 base pairs
12
Q
DNA consists of ___ long polynucleotide chains with ____ types of nucleotide subunits
A
2, 4
13
Q
Purines
A
Adenine
Guanine
14
Q
Pyrimidines
A
Cytosine
Thymine
15
Q
Adenine pairs with thymine with ___ hydrogen bonds
A
2
16
Q
Guanine pairs with cytosine with ____ hydrogen bonds
A
3
17
Q
DNA serves as it’s own
A
template
18
Q
DNA is enclosed in the
A
Nucleus
19
Q
Eukaryotic DNA is packaged into
A
chromosomes
20
Q
The human genome is _____ nucleotides distributed over ___ different chromosomes
A
3.2 x 10^9, 24
21
Q
each chromosome is single long _____ DNA molecular associated with proteins that fold and pack it into compact structure
A
Linear
22
Q
Packaging of DNA into a chromosome is similar to packing 24 miles of thread into a
A
tennis ball
23
Q
DNA + protein =
A
chromatin
24
Q
each human cell contain 2 copies of each chromosome (maternal and paternal homologs) except for ___ and ____
A
germ cells and RBCs
25
humans have ____ pair of autosomes and ___ sex chromosomes
22, 2 (46 total chromosomes)
26
Banding pattern of chromosomes can be seen with _____ stain under light microscopy
Giemsa stain
27
The used of a Giemsa stain to show banding pattern of chromosomes is used to
identify and number chromosomes
28
Banding pattern seen with Giemsa stain under high microscopy is still used in
cytogenetics laboratories for karyotype analysis
29
Cytosine techniques are very helpful in recognizing
chromosomal translocations
30
Chromosomal translocations can occur during an
abnormal recombination event
31
Balanced translocations maintain
the correct amount of genetic material
32
Translocations frequently occur in
cancer cells
33
Translocation of chromosomes 9 and 22 form the ______ chromosome on Chromosome 22, commonly found in chronic myelogenous leukemia (BCR-ABL fusion gene)
Philadelphia chromosome
34
Translocation of chromosomes ___ and ___ form the Philadelphia chromosome on Ch 22, commonly found in chronic myelogenous leukemia (BCR-ABL fusion gene)
9 and 22
35
What information is found on chromosomes
- Genes
- Encoding proteins
- Encoding RNA molecules
- Interspersed DNA that does not contain genes
- Regualtory information
- "junk" DNA
36
exon
Translated portion of gene
37
Intron
non-coding portion of gene
38
First draft of the Human genome project was in ____ and finished sequence published in ____
2001, 2004
39
Large average gene size, with only ____% of the gene comprising coding region (mostly intronic sequence)
5%
40
Percentage of DNA sequence in exons (protein-coding sequences)
1.5%
41
Percentage of DNA in other highly conserved sequences
3.5%
42
Percentage of DNA in high-copy-number repetitive elements
approximately 50%
43
DNA length
3.2 x 10^9 nucleotide pairs
44
Number of genes coding for proteins
approximately 21,000
45
Largest gene coding for protein
2.4 x 10^6 nucleotide pairs
46
Mean size for protein-coding genes
27,000 nucleotide pairs
47
smallest number of exons per gene
1
48
Larges number of exons per gene
178
49
Mean number of exons per gene
10.4
50
Largest exon per size
17,106 nucleotide pairs
51
Mean exon size
145 nucleotide pairs
52
number of noncoding RNA genes
Approximately 9000
53
Number of pseudogenes
more than 20,000
54
What is a pseudogene
a DNA sequence closely resembling that of a functional gene, but containing numerous mutations that prevent its proper expression or function
55
during _____ chromosomes are replicated, they are decondensed and can't be easily distinguished
interphase
56
During ____ chromosomes become highly condensed and separated into two daughter nuclei
Mitosis
57
what are the requirements for a copy to be passed on to each daughter cell at division
- Requires replication
- Separation of copies
- Partitioning to daughter cells
58
Where duplication of the DNA begins
DNA replication origin
59
Allows one copy of each duplicated and condensed chromosome to be pulled into each daughter cell when the cell divides.
Centromere
60
The ______ protein complex attaches to the centromere
Kinetochore
61
At the ends of a chromosome, contain repetitive sequences that enable the ends to be efficiently replicated
Telomeres
62
Mitotic chromosomes are condensed _____ times compared to interphase DNA
500
63
_____ situation: must allow rapid localized access to DNA for gene expression
Dynamic
64
DNA binding proteins involved in forming chromosomes include ____ and ______ chromosomal protiens
histones and non-histone
65
Protein + nuclear DNA =
Chromatin
66
_____ is the most basic unit of chromosome packing is the nucleosome
Nucleosome
67
if chromosome is partially unfolded it forms
beads on a string (string= DNA, beads= DNA wound around histones)
68
Chromatin isolated directly from interphase nucleus forms ____nm thick thread
30nm
69
Digestion with nucleases break down DNA by cutting between _____ and degrading the exposed DNA between ______
between nucleosomes and degrading the exposed DNA between nucleosome core particles (linker DNA)
70
Each individual nucleosome core particle consists of ____ histone proteins. ___ Molecules each of ____, ______, _____, _____ and ____ stranded DNA that is ______ nucleotide pairs long
8 (histone octamer)
- 2 molecules of each H2A, H2B, H3, H4
- 2x stranded DNA that is 147 nucleotide pairs long
71
Linker DNA can be ____ to ____ nucleotides
few to 80 nucleotides
72
Nucleosomes repeat every ____ nucleotide pairs or so
200
73
Histones are small proteins with common structural motif called
histone fold
74
high resolution structure of nucleosome core particle is disc-shaped with DNA wrapped _____ turns
1.7
75
Nucleosomes have an _________ that extends out form the core and are subject to covalent modifications important for chromatin regulation
N terminal amino acid tail
76
_____ hydrogen bonds are formed between DNA and the histone core in each nucleosome
142
77
How is DNA packaged
- 142 hydrogen bonds are formed between DNA and the histone core in each nucleosome
- Hydrophobic interactions
- Salt linkages
- lysine and arginine (positive charges) comprise more than 1/5 of histone residues; effectively neutralize negative charged DNA backbone
78
____ and _____ Comprise more than 1/5 of histone residues; effectively neutralize negatively charged DNA backbone
Lysine and Arginine
79
Histones are _____ conserved meaning most changes would be
highly conserved meaning most changes would be lethal
80
Only __ histone differences between pea and cow H4
2
81
Specialized _______ add to various possible chromatin structures
variant histone proteins
82
Nucleosomes are in a constant state of
flux
83
DNA is unwrapped in the nucleosome ____ times per second, and remains unwrapped for ______ milliseconds before tightening up again
- 4 times per second
| - 10-50 milliseconds
84
Chromatin remodeling complexes allow further loosening of _____
DNA/Histone contact
85
Proteins are related to helicases and are ____ dependent; bind to both protein core and DNA
ATP
86
Repeated cycles catalyzes nucleosome sliding, making DNA available to other
proteins in the cell
87
Nucleosome packing forms a dense fibrous structure with diameter of
30nm
88
Nucleosome packing maybe by ____ model, stacking may be facilitated by histone tails (esp ____)
zig-zag, H4
89
Histone ____ "linker histone" is present in 1:1 ratio with nucleosome cores
H1
90
Histone tails are largely _____, suggesting that they are highly flexible
unstructured
91
Histone trials can form interactions with
adjacent nucleosomes
92
What is the largest histone protein
H1
93
Linker histone
H1
94
Is H1 well conserved
yes
95
H1 (linker histone) contacts both ___ and ___
DNA and protein
96
H1 (linker histone) changes the path of the DNA as it exits the
nucleosome
