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Genetics > 11| CHROMOSOME STRUCTURE AND DNA SEQUENCE ORGANIZATION > Flashcards

11| CHROMOSOME STRUCTURE AND DNA SEQUENCE ORGANIZATION Flashcards

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1
Q

Eukaryotic cells, in contrast to viruses and bacteria, contain relatively large amounts of DNA organized into nucleaosomes and present during most of the cell cycle as….

A

chromatin fibers

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2
Q

A stretch of DNA that repeats many times in a Genome. More than 50% of the genome consists of this….

A

repetitive DNA

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3
Q

Can be used as genetic markers (such as in finger-printing)

A

repetitive DNA

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4
Q

term for highly repetitive DNA

A

Satalite DNA

-5% of the genome, viable and short

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5
Q

in situ molecular hybridization defines what type of repetitive DNA

A

Satalite DNA

-5% of the genome, viable and short

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6
Q

terms middle repetitive DNA

A

Tandom repeats and interspersed retrotransposons

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7
Q

What are the three tandom repeats?

What are there genetic markers?

A

middle repetitive DNA = Tandom repeats and interspersed retrotransposons

Tandom repeats:

  1. multi - rRNA
  2. mini - VNTRs
  3. micro- STRs
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8
Q

What are the two interspersed retrotransposons?

What are there genetic markers?

A

middle repetitive DNA = Tandom repeats and interspersed retrotransposons

interspersed retrotransposons:

  1. SINEs - Alu
  2. LINEs - L1`
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9
Q

of the two interspersed retrotransposons which is more abundant in the genome?

A

LINEs 21%

SINEs are only 13%

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10
Q

Multiple copies of genes present in multiple numbers in the genome, termed

A

multi tandom repeats (rRNAs)

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11
Q

in this region, motifs of 10-60bp are repeated 5-50 times, is termed

A

mini tandom repeats (VNTRs)

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12
Q

1-6bp repeating 5-50x

A

micro tandom repeats (STRs)

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13
Q

short interspersed nuclear elements that are non-coding 100-700bp in length

A

SINEs (interspersed retrotransposons middle repetitive DNA)

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14
Q

Long interspersed nuclear elements of 7,000 bp

A

LINEs (interspersed retrotransposons middle repetitive DNA)

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15
Q

What are the uses of the following genetic markers

  1. rRNA
  2. VNTRs
  3. STRs
A
  1. rRNA - taxonomy
  2. VNTRs - Finger-printing
  3. STRs - comparing loci
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16
Q

VNTRs a middle tandem repeat under micro repetative sequences stands for ….

A

Viable No Tandem Repeats

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17
Q

What are the uses of the following genetic markers

  1. Alu
  2. L1
A
  1. Alu - movement/ ancestry in human populations

2. L1 - identifies L1 insertion in any DNA samples

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18
Q

How are STRs used to identify individuals?

A

to compare specific loci on DNA from multiple samples, it is stable and predictable

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19
Q

micro satellite which can be amplified by PCR without mixing other genes in ordegrading it?

A

Short tandem repeats, STRs

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20
Q

Where is Satellite DNA found

A

Heterochromatin, in the centromeres/ telomeric regions.

  • large amounts of non-coding tandomly repeating sequences
  • 5%
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21
Q

“Jumping genes”, found throughout the genome in single copies making up 45%, termed

A

intertransposons

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22
Q

the three various categories of repetative DNA are

A
  1. satellite DNA
  2. Tandem Repeats
  3. Interspersed retrotransposons
    - they differ in position, sequence, location and presence or absence of coding regions
23
Q

What is the difference between heterochromatin and euchromatin? give examples of where you would find each?

A

Heterochromatin - genetically less active, tightly packed, only in eukaryotes. maintains structural integrity.

ie: bar bodies, X-chromosome of females and centromeric/ telomeric regions in the Y-chromosome of males

euchromatin- most active portion of the genome accounting 92%. allows genes to be transcribed and for genetic variation to occur

24
Q

describe the exact composition and arrangement of the nucleosome

A

Its core parasiticals contain two copies of each histone protein (H2: A B 3 and 4) and it is 146 bp of super helical DNA wrapped around a histone octomer

25
Q

a structural unit of a eukaryotic chromosome, consisting of a length of DNA coiled around a core of histones.

A

nucleosome

26
Q

What genetic processing is occuring in a puff of a polytene chromosome?

A

RNA transcription

27
Q

The bands of _______ chromosomes become enlarged at certain times to form swellings called a ______

A

The bands of Polytene chromosomes become enlarged at certain times to form swellings called puffs.

Polytene chromosomes- found in various tissues; salivary, rectal. Individual bands are sometimes called chromeres.

28
Q

What important information did lampbrush and polytene chromosomes show?

A

during interphase polyetenes have a distinct think/thin banding patterns which were at first used in mapping chromosomes to identify small mutation/ taxonomic identification

now they are used to study the function of genes in transcription

29
Q

these chromosomes are a special form of chromosome found in the growing oocytes of most animals, except mammals.

A

Lampbrush chromosomes

30
Q

ellipsoidal symmetrical shape accross 3 axis and large, this defines a chloroplast DNA or a mitochondrial DNA

A

chloroplast DNA

  • both contain a double membrane, their own DNA, synthesis machinery and are involved in energy metabolism and photosynthesis
31
Q

Oblong in shape but over time can rapidly change its shape and is small, this defines a chloroplast DNA or a mitochondrial DNA

A

mitochondrial DNA

  • both contain a double membrane, their own DNA, synthesis machinery and are involved in energy metabolism and photosynthesis
32
Q

bacterial chromosomes are relativly simple in form. they generally consist of a double stranded DNA molecule, compacted into a structure sometimes referred to as the…

A

Nucleoid

33
Q

in contrast to eukaryotes, bacteriophage and bacterial chromosomes are largely devoid of associated proteins, are much smaller in size, and most often circular

A

largely devoid of associated proteins, are much smaller in size, and most often circular

34
Q

Defined as a nucleoprotein organized into repeating units called nucleosomes, an octomer of four types of histones

A

Eukaryotic chromatin

-part of chromatin that remains relatively uncoiled in and replicates much earlier in division

35
Q

Bead-like structure in eukaryotic chromatin, composed of a short length of DNA wrapped around a core of histone proteins

A

nucleosomes

36
Q

protein molecules around which DNA is tightly coiled in chromatin

A

histones

37
Q

modification of histone tails via acetylation, methylation, ubiquitination, and phosphorylation, all examples of gene regulation is defined as

A

Chromatin Remodeling

38
Q

Tandemly repeating, non-coding DNA, found in heterochromatin

A

satellite DNA

39
Q

viruses with double stranded closed loops of DNA on the protein coat

A

phi X174 bacteriophage & polyoma virus

40
Q

compact DNA structure in bacteria can be termed a

A

neucleoid

41
Q
  1. Sizes vary greatly by organism

2. Uniform in size among different organisms

A

mitochondrial DNA - Sizes vary greatly by organism

2.chloroplast DNA - Uniform in size among different organisms

42
Q

basic positively charged proteins in eukaryotic chromatin are called

A

histones

43
Q

When chromatin is induced to change it’s structure in order to facilitate protein-DNA interactions, this process will happen

A

chromosome remodeling

  • is the dynamic modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression.
44
Q

acetylation, methylation, ubiquitination and phosphorylation all modify what

A

chemical processes that that modify histones and are important to genetic function

45
Q

hybridizes special radioactive DNA with DNA in chromosomes is termed

A

in situ molecular hybridization

-satalite DNA, 5%, highly repetitive

46
Q

____________ are the most common sites of post-translational modifications.

A

Histone tails

47
Q

What are the three post-transcriptional modifications

A
  1. cap and tail (stabilize and protect from degradation)
  2. splicing introns
  3. Modification of RNA to be used as a template in translation
48
Q

What are the six post- translational modifications

A
  1. removal of N and C termis; amino acid methonine
  2. phosphorylation; modifification of proteins shape/ chemical nature
  3. Glycoproteins; “the golgi-bodies”; adding carbon side chains, glycosylation
  4. cleaving of the polypeptide chains
  5. Signal sequences a re removed (written in the genome)
  6. PP chains interact with metals. ie: hemoglobin and 4 iron atoms
49
Q

adding carbon side chains can be termed as

A

glycosylation

  • a post- translational modifications adding carbon side chains
50
Q

What is the enzyme that acetylates the histones?

A

histone acetyltransferase (HAT)

51
Q

it is the addition of a methyl group to arginine or lysine residues in histones

  • that causes DNA to be wrapped more tightly along histones
  • thus silencing expression of the gene
A

methylation

52
Q

What enzyme phosphorylates the histones?

A

histone kinases

53
Q

T or F: The vast majority of Euk genome does NOT encode functional genes

A

True

-only a small portion of Euk genome (2-10%) constitutes protein-encoding genes

54
Q

What are psudogenes?

A

they are large number of single-copy noncoding regions where

1) DNA sequences that represent evolutionary vestiges
2) have undergone significant mutational alterations (insertions and deletions)
3) are NOT transcribed

Genetics (9 decks)

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