Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MOLECULAR BIO > EXAM 2 > Flashcards

EXAM 2 Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

what is a chromosome

A

A discrete unit of the genome carrying many genes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what does each chromosome consist of

A

Each consists of a very long molecule of duplex DNA and an approximately equal mass of proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how are chromosomes visible

A

visible as a morphological entity only during cell division (specifically during metaphase).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is a nucleoid

A

The structure in a prokaryotic cell that contains the genome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

where is the DNA bound in a nucleoid

A

DNA is bound to proteins and is not enclosed by a membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is chromatin

A

The state of nuclear DNA and its associated proteins during the interphase (between mitoses) of the eukaryotic cell cycle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the packing ratio

A

ratio of the length of DNA to the unit length of the fiber containing it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

who coins the term chromatin

A

Fleming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what did Walter Fleming do

A

used dyes to stain chromatin during cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what percentage of cells are in interphase

A

80-90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what percentage of cells are in metaphase

A

2%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what halts cells in metaphase

A

colchicine (mitotic spindle inhibitor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the stages of mitosis

A

PPMAT-C

  1. prophase
  2. prometaphase
  3. metaphase
  4. anaphase
  5. telophase
  6. cytokinesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are 4 key points for prophase

A
  1. chromosomes condense and become visible
  2. spindle fibers emerge from the centrosomes
  3. nuclear envelope breaks down
  4. nucleolus disappears
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are 4 key points for prometaphase

A
  1. chromosomes continue to condense
  2. kinetochores appear at the centromeres
  3. mitotic spindle microtubules attach to kinetochores
  4. centrosomes move toward opposite poles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are 3 key points for metaphase

A
  1. mitotic spindle is fully developed, centrosomes are at opposite poles of the cell
  2. chromosomes are lined up at the metaphase plate
  3. each sister chromatid is attached to a spindle fiber originating from opposite poles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are 3 key points for anaphase

A
  1. cohesion proteins binding to the sister chromatids together to break down
  2. sister chromatids (now called chromosomes) are pulled towards opposite poles
  3. non-kinetochore spindle gibers lengthen, elongating the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are the 3 key points for telophase

A
  1. chromosomes arrive at opposite poles and begin to decondense
  2. nuclear envelope material surrounds each set of chromosomes
  3. the mitotic spindle breaks down
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are 2 key points for cytokinesis

A
  1. animal cells: a cleavage furrow separates the daughter cells
  2. plant cells: a cell plate separates the daughter cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

iCLICKER: which of the following is not a stage of mitosis

A. interphase
B. prophase
C. metaphase
D. anaphase
E. telophase

A

A. interphase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what are viral genomes packaged into

A

their coats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is a capsid

A

external protein coat of a virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are 2 ways capsids can be inserted

A
  1. assembled around the nucleic acid (single stranded RNA viruses)

OR

  1. constructed as an empty shell into which the nucleic acid is inserted (DNA viruses)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is limited by the structure of the head shell

A

the length of DNA that can be incorporated into a virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

nucleic acid within the head shell is…

A

extremely condensed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is Boveri and Sutton’s chromosome theory of inheritance state

A

genes are found at specific locations on chromosomes, and that the behavior of chromosomes during meiosis can explain Mendel’s laws of inheritance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what occurs in a capsid assembled around nucleic acid

A

Filamentous RNA viruses condense the RNA genome as they assemble the head shell around it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what occurs in a capsid constructed as an empty shell and nucleic acid is inserted

A

Inserting DNA into a phage involves translocation and condensation. (energetically unforgivable = terminase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is terminase

A

an enzyme that cleaves multimers of a viral genome and then uses hydrolysis of ATP to provide the energy to translocate the DNA into an empty viral capsid starting with the cleaved end. (energetically unforgiveable)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

bacterial genomes are organized into

A

substructures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what do proteins do for bacterial DNA

A

help with organization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

how is the bacterial nucleoid organized

A

multiple loops compacted by nucleoid-associated proteins such as H-NS and HU

33
Q

what are the different proteins and their roles

A
  1. H-NS (histone like) - gene promoter activity
  2. HU (histone like) - DNA flexibility, DNA metabolism
  3. IHF - nucleoid architecture, more genetic processes
  4. Dps - DNA protection during starvation
  5. Condensins - regulate chromosome, condensation, segregation
34
Q

iCLICKER: the enzyme terminase is responsible for
a. formation of eukaryotic centromeres
b. packaging a phage genome into its capsid
c. the decondensation of eukaryotic chromatin
d. supercoiling bacterial DNA
e. formation of eukaryotic telomeres

A

b. packaging a phage genome into its capsid

35
Q

eukaryotic DNA has ____ and domains attached to a ____

A

has loops and domains attached to a scaffold

36
Q

DNA of interphase chromatin is ______ ______ into _______ domains avergaing 85 kb

A

interphase chromatin is negatively supercoiled into independent domains

37
Q

what do metaphase chromosomes have and what are they

A

protein scaffold (which loops of supercoiled DNA are attached)

38
Q

what do specific sequences attach DNA to

A

interphase matrix (more disperse structure is the support)

39
Q

what is the matrix attachment region (MARs)

A

DNA is attached to the nuclear matrix at specific sequences called matrix attachment regions

40
Q

The MARs are ______ rich but do NOT have any _____ _____ sequence

A

MARs are A-T rich but do NOT have any specific consensus sequence

41
Q

what do linker histones and other proteins allow DNA to do

A

curl even more

42
Q

as you go through the cycle, what happens to scaffolding proteins what does it lead to?

A

there is more scaffolding proteins and more condensation

43
Q

when can we see individual chromosomes

A

ONLY DURING MITOSIS

44
Q

what two things is chromatin divided into

A

euchromatin and heterochromatin

45
Q

during interphase, the general mass of chromatin is in the form of

A

euchromatin (slightly less tightly packed than mitotic chromosomes = loose and able to be read/expressed

46
Q

during interphase what remains densely packed

A

regions of heterochromatin (packed and not read/expressed)

47
Q

what is constitutive heterochromatin and examples

A

its stable and permanent and examples are telomeres and centromeres

48
Q

what is the chromocenter

A

an aggregate of heterochromatin from different chromosomes

49
Q

what are chromosome territories

A

chromosomes appear to occupy distinct 3- dimensional spaces

50
Q

what is constitutive heterochromatin
a. contains regions of repetitive DNA
b. is permanently condensed
c. has reduced density of genes
d. all of these are correct

A

d. all of these are correct

51
Q

the G bands are lower in ____ content than the _____ what do the band colors represent

A

G bands are lower in G-C content than the interbands

white = genes, euchromatin
dark = dense, heterochromatin, can’t be accessed

51
Q

what does Giemsa staining techniques

A

cause chromosomes to have the appearance of striations, which are called G-bands

52
Q

what is a centromere

A

constricted region of a chromosome that includes the site of attachment (the kinetochore) to the mitotic or meiotic spindle.

53
Q

what is the acentric fragment

A

A fragment of a chromosome (generated by breakage) that lacks a centromere and is lost at cell division.

54
Q

what is microtubule organizing center (MTO)

A

a region from which microtubules emanate.

55
Q

in animal cells what is the major microtubule organizing center

A

centrosome

56
Q

where is a eukaryotic chromosome held

A

on the mitotic spindle by the attachment of microtubules to the kinetochore that forms in its centromeric region.

57
Q

iCLICKER: the structure that attaches a chromosomes to a microtubule is called a(an)
A. centriole
B. MAR
C. kinetochore
D. spindle
E. MTOC

A

C. kinetochore

58
Q

what causes the centromere to form

A

its believed to be due to proteins

59
Q

what are centromeres characterized by

A

centromere-specific histone H3 variant and often have heterochromatin that is rich in satellite DNA seqeunces

60
Q

what is CenH3

A

the primary determinant in establishing functional centromeres and kinetochore assembly sites

61
Q

centromeres are specified epigentically by

A

chromatin structure (centromere-specific histone H3; CenH3)

62
Q

what do centromeres in higher eukaryotic chromosomes contain large amounts of

A

repetitive DNA and unique histone variants, but the function of repetitive centromeric DNA not known

63
Q

what do regional centromere contain

A

centromeric histone H3 variant and repetitive DNA

64
Q

what elements are identified in S. cerevisia and what do they do

A

CEN elements by the ability to allow a plasmid to segregate accurately at mitosis (attach chromosome to spindle)

65
Q

what is the telomere required for

A

stability of the chromosome end

66
Q

telomeric sequence are characterized in many ______; same type of sequence is found in ___ and ____

A

eukaryotic cells; same type of sequence is found in plants and animals.

67
Q

what does a telomere consist of

A

simple repeat where a G-T-rich strand at the 3ʹ terminus typically extends beyond the C-A-rich strand (general form of sequence: (T/A)1–4 G>2).
- G-T rich strand has overhang

68
Q

what do telomeres promote

A

pairing, and recombination during meiosis via links to the cytoskeleton through nuclear envelope proteins

69
Q

what do telomeres play a role in

A

aging, cancer and cell differentiation

70
Q

what are telomeres three widely conserved functions

A
  1. protect the chromosome ends
  2. allow the telomere to be extended (so it is not shortened with each replication cycle).
  3. Facilitate meiotic chromosome reorganization (pairing and recombination of homologous chromosomes).

PROTEINS BOUND TO THE TELOMERES CONTRIBUTE TO THESE FUNCTIONS

71
Q

what is a telomerase

A

(a ribonucleoprotein) uses the 3′–OH of the G+T telomeric strand and its own RNA template to iteratively add tandem repeats (5′-TTAGGG-3′ in human) to the 3′ end at each chromosomal terminus.

72
Q

what is telomerase expressed in

A

actively dividing cells and is not expressed in quiescent, or non-dividing terminally differentiated cells.

73
Q

what is quiescence

A

the reversible state of a cell in which it does not divide but retains the ability to re-enter cell proliferation.

74
Q

what do loss of telomeres inhibit

A

successful cell division, resulting in chromosome breaks, translocation and increased rates of mutation.

75
Q

what do loss of telomeres result in

A

a loss of viability and cellular senescence - irreversible cell cycle arrest.

76
Q

telomeres shorten with

A

age

77
Q

iCLICKER: which of the following is not a telomeric function
a. allowing extension of the telomere
b. facilitating chromosome reorganization for efficient pairing and recombination of homologous chromosomes during meiosis
c. protection of the chromosome end
d. providing a site of origin for DNA replication
e. all of these are telomeric functions

A

d. providing a site of origin for DNA replication

78
Q

T/F: in a cell line where telomerase gene has been knocked out (ex: no expression), chromosome ends will be lengthened

A

FALSE

MOLECULAR BIO (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions