Brainscape's Knowledge GenomeTM

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


See full index

biology hl > D2.1 Cell and nuclear division SL > Flashcards

D2.1 Cell and nuclear division SL Flashcards

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

general characteristics of diploids

A
  • 2n
  • 46 chromosomes
  • e.g. somatic cells
  • mitosis
  • most human cells
  • genetically identical
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

general characteristics of haploids

A
  • n
  • 23 chromosomes
  • e.g. gametes
  • meiosis
  • purpose: genetic variation, create offspring (prevent extinction from disease etc.)
  • unique from each division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

structure of DNA inside the nucleus

A

DNA is supercoiled inside the nucleus

  • If we uncoil the DNA from one human nucleus, it can reach up to 2m long
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is chromatin

A
  • Chromatin is made of DNA and histone and supercoiled into nucleosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

give example of supercoiling

A

when DNA is wrapped around histone proteins

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

What happens to chromatin during prophase

A
  • Chromatin will condense into chromosome during prophase of mitosis and meiosis for easier transport during cell division
  • Chromosome is visible under microscope
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

do eukaryotes have supercoiling?

A

no, but prokaryotes do

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

examples of supercoiling

A
  • when DNA is wrapped around histone proteins (8)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

DNA is usually in what structure?

A

chromatin

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

what is nucleosome made of

A

made of DNA and 8 histone proteins

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

why does mitosis have to occur

A
  • maintain a good surface area to volume ratio
  • repair
  • growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the X shape chromosome and what does it mean

A

X shaped chromosomes → about to go through nuclear division (mitosis/meiosis)

  • condensed chromosome → X shape
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many chromosomes are there inside the nucleus

A
  • There are 23 pairs of chromosomes inside the human nucleus
  • 46 chromosomes in total
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What pair of chromosomes determines the gender?

A

Sex chromosomes

  • One of the 23 pairs is called the sex chromosomes → determine gender
    • XY male
    • XX female
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What combination of chromosomes give male & which gives female

A

XY male
XX female

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the other 22 pairs of chromosomes called

A

autosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the other 22 pairs of chromosomes called

A

autosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What causes Down syndrome?

A
  • Trisomy (21) chromosome = down syndrome
    • presence of 3 chromosomes instead of a pair
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the chromosomes from mother & father called

A
  • from dad = paternal chromosome
  • from mom = maternal chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does karyogram show

A

shows karyotype

-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

homologous chromosomes have the same () in the same ()

A

homologous chromosomes have the same genes in the same position (loci)

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

Phenotype

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

Genotype

A
  • combination of alleles that determine the phenotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

gene from mom and dad are ()

what does it mean?

A

gene from mom and dad are homologous

  • gene found in same place (e.g. for hair)
24
Q

Gene

A

Gene is a length of DNA that contains the genetic information to synthesise a polypeptide (not protein yet)

25
Q

name of top/bottom part of chromosome

A
  • p arm = top part of chromosome
  • q arm = bottom part of chromosome
26
Q

name of part that separates top and bottom part of chromosome

A

centromere

*count centromere to count number of chromosomes

27
Q

what stores genes?

A

DNA

DNA is chemical which stores this coded instruction (4 bases: ATGC)

28
Q

why do chromosomes become double stranded?

most of the time, chromosomes are single stranded

A

only just before the cells need to divide, the chromosomes will make a copy of themselves via DNA replication to form duplicated chromosome and they will form the shape of an X

*-right before replication, chromatin condense into single stranded chromosome structure → have to replicate/duplicate DNA for new cell

  • only when need to replicate DNA → double stranded
  • single stranded happens during interphase (s phase) [HL only]*
29
Q

describe process of replication of chromosome

A

homologous chromosome —replication→ homologous chromosome pairs (bivalent)

  • each = chromatid
  • when the same (due to X shape) → sister chromatids
  • the 2 X’s = non sister chromatids
30
Q

How is meiosis different from mitosis?

(Just focusing on chromosome 1)

A

mitosis = 1 division

meiosis = 2 division + reduction (2n to n)

31
Q

Define meiosis

A

the reduction division of a parent diploid nucleus to form four unique daughter haploid nuclei.

meiosis is needed to form gametes

32
Q

Define mitosis

A

the nuclear division of a parent diploid nucleus to form two identical daughter diploid nuclei

33
Q

what happens to the cell before mitosis?

A

the cell will grow in size, replicates the DNA and make more organelles (e.g. mitochondria, microtubule organising centre MTOC) during interphase

34
Q

can we see the chromosomes during interphase?

A

No

because in form of chromatins

35
Q

if cell go through mitosis, need how many MTOC/centriole

A

2

36
Q

outline the process of mitosis & give its acronym

A

P.MAT

mitosis acronym: PMAT

1) prophase
2) metaphase
3) anaphase
4) telophase

37
Q

BEFORE MITOSIS

what happens during interphase?

[bioninja]

A
  • DNA is present as uncondensed chromatin (not visible under microscope)
  • DNA is contained within a clearly defined nucleus
  • Centrosomes and other organelles have been duplicated
  • Cell is enlarged in preparation for division
38
Q

MITOSIS

what happens during prophase?

[bioninja]

A
  • DNA supercoils and chromosomes condense (becoming visible under microscope)
  • Chromosomes are comprised of genetically identical sister chromatids (joined at a centromere)
  • Paired centrosomes move to the opposite poles of the cell and form microtubule spindle fibres
  • The nuclear membrane breaks down and the nucleus dissolves

(- chromatins will condense during early prophase (become X shape)
- nucleus disappears by end of prophase → degenerates
- spindle microtubule is made of tubulin
- because nucleus degenerates → sister chromatids free to move around → move to cell equator)

39
Q

MITOSIS

what happens during metaphase?

[bioninja]

A
  • Microtubule spindle fibres from both centrosomes connect to the centromere of each chromosome
  • Microtubule depolymerisation causes spindle fibres to shorten in length and contract
  • This causes chromosomes to align along the centre of the cell (equatorial plane or metaphase plate)

[MTOC will produce spindle microtubule to attach to the centromeres (specifically the kinetochores)]

40
Q

MITOSIS

what happens during anaphase?

[bioninja]

A
  • Continued contraction of the spindle fibres causes genetically identical sister chromatids to separate
  • Once the chromatids separate, they are each considered an individual chromosome in their own right
  • The genetically identical chromosomes move to the opposite poles of the cell
41
Q

MITOSIS

what happens during telophase?

[bioninja]

A
  • Once the two chromosome sets arrive at the poles, spindle fibres dissolve
  • Chromosomes decondense (no longer visible under light microscope)
  • Nuclear membranes reform around each chromosome set
  • Cytokinesis occurs concurrently, splitting the cell into two
42
Q

what binds to the kinetochore of the centromere and what does it form?

A

cohesin, forms cohesin loops

43
Q

function of cohesin

A

binds the chromatids together

44
Q

describe cytokinesis in animal cells

A
  • a cleavage furrow is created using a ring of contractile protein, actin and myosin
  • the cleavage furrow reaches the centre
  • the cells are pinched apart into two, separate into daughter cells
45
Q

describe cytokinesis in plant cells

A
  • vesicles moved to the equator where they fuse to form tubular structures across the equator
  • tubular structures merge to form two plasma membranes of the two daughter cells → completion of cell division (cell plate)
  • pectins and other substances deposited between the two membranes by exocytosis, forming the middle lamella. cellulose is brought to the middle lamella by exocytosis
  • cells walls are formed adjacent to the equator
46
Q

name of the holes in the plant cell wall

A

plasmodesmata

47
Q

example for unequal cytokinesis

A

1) oogenesis in humans (human egg/oocyte)

  • polar body etc.

2) yeast budding

48
Q

describe crossing over

A
  • only occurs in prophase 1 (only occurs when there is bivalent)

1) synapsis → homologous chromosomes associate (the bivalent get closer together)

2) chiasma formation → neighbouring non-sister chromatids are cut at the same point; a holliday? junction forms as the DNA of the cut sections attach to the open end of the opposite non-sister chromatid

3) recombination → alleles are swapped between the non-sister chromatids

49
Q

does crossing over always occur and what factors influences the likelihood of it happening?

A

does not always happen

  • more likely if have longer chromosome

if further away from centromere → crossing over more likely to occur

usually happens in q arm bc longer

50
Q

what is the name of the cross when the chromosomes cross over

A

chiasma

51
Q

name of new chromosome after crossed over

A

new chromosome = recombinant

52
Q

demonstrate crossing over if L ee R EE

A

cross over becomes L eE R eE

53
Q

purpose of crossing over

A

further enhance genetic variation

54
Q

what is non-disjunction and when can it occur?

A

(when chromosomes fail to separate correctly)

  • can occur in anaphase 1 or 2
  • missing chromosome: dead fetus
  • if extra 21 chromosome
55
Q

outline what happens during Meiosis I

A
  • interphase: DNA replication takes place in synthesis phase. chromosomes are replicated, making pairs of sister chromatids.
  • prophase I: (homologous pairs) bivalent associate. crossing-over can take place, resulting in the exchange of alleles between non-sister chromatids
  • metaphase l: homologous pairs align at the equator
  • anaphase l: homologous pairs are separated. this is the reduction division. non-disjunction can occur here.
  • telophase l: new nuclei are formed and cytokinesis begins. nuclei contain pairs of sister chromatids, but no bivalent 1(homologous pairs)
56
Q

outline what happens during meiosis ll

A
  • interphase: no DNA replication in this interphase
  • prophase ll: no crossing-over takes place
  • metaphase ll: sister chromatids align at the equator
  • anaphase ll: the centromere is broken and sister chromatids are separated. non-disjunction can occur here
  • telophase ll: new nuclei are formed and cytokinesis begins. four haploid gamete cells are produced.
57
Q

DIFFERENCES BETWEEN MITOSIS AND MEIOSIS

in terms of:

  1. number of divisions
  2. type of cells produced
  3. does crossing over occur?
  4. does chiasmata form?
  5. do the homologous pairs associate as bivalent?
  6. what separates in anaphase?
A

mitosis
1. one division
2. diploid cells produced
3. no crossing over in prophase
4. no chiasmata formation
5. homologous pairs do not associate and line up at the equator in metaphase
6. sister chromatids separate in anaphase

meiosis
1. two divisions
2. haploid gametes produced
3. crossing over in prophase l
4. chiasmata form
5. homologous pairs associate as bivalents and lined up at the equator in metaphase l
6. bivalent (homologous pairs) separate in anaphase l ; sister chromatids separate in anaphase ll

58
Q
A

biology hl (19 decks)

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