Brainscape's Knowledge GenomeTM

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


See full index

Wjec Biology As Unit 1 > 1.6 > Flashcards

1.6 Flashcards

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

What do chromosomes consist of

A

DNA and histone

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

When are chromosomes visible

A

After they condense at the onset of cell division

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

Following DNA replication what does a chromosome exist as

A

Two identical sister chromatids joined by the centromere

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

What do chromosomes contain

A

Genes that code for specific polypeptides

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

How manu chromosomes do humans have

A

46

23 pairs

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

What are homologous chromosomes?

A

Chromosomes that are the same size and shape and carry the same genes but these may be different versions called alleles.
One chromosome of
each pair comes from each
parent

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

Two complete sets of chromosomes

A

Diploid 2n

Humans - 46

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

What is haploid and where are haploid numbers found

A

n

Human gametes

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

What are the stages of the cell cycle

A

Interphase
Mitosis
Cytokines

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

Define interphase

A

a period of synthesis and growth during the cell cycle

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

Describe interphase

A
  • longest cell cycle phase
  • very metabolically active
  • DNA quantity doubles (chromosome number remains as it becomes 2 sister chromatids)
  • protein synthesis
  • organelle replication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is mitosis

A

Chromosomes are arranged and separated prior to cell division
Results in two genetically identical cells that contain the same number or chromosomes as the parent cell

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

What happens during prophase of mitosis

A

• Chromosomes condense to become shorter and thicker
• Chromosomes become visible as two sister chromatids attached by a centromere
• Centrioles move to opposite
poles (not higher plants)
• Nuclear envelope disintegrates
• Nucleolus disappears

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which stage

A

Prophase of mitosis

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

What happens during metaphase of mitosis

A
  • Spindle forms

* Chromosomes align at the equator of the cell attached to spindle microtubules via centromere

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

Which stage

A

Metaphase of mitosis

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

What happens during anaphase of mitosis

A
  • Spindle fires shorten

* Centromeres divide, and chromatids are pulled towards opposite poles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which stage

A

Anaphase of mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens during telophase of mitosis

A 
• Chromatids reach poles and
become indistinct by uncoiling
• Nuclear envelope reforms
• Nucleolus reforms
• Spindle disintegrates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which stage

A

Telophase of mitosis

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

What is cytokinesis

A

the division of the cytoplasm to form

two daughter cells

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

Animal cytokinesis

A

membrane infolds via cleavage furrow until the two cells become separated

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

Plant cell cytokinesis

A

Cell plate develops from the centre outwards until the cell is divided into two

24
Q

Why is animal and plant cytokinesis different

A

Plants have cellulose cell walls which prevents them from forming a cleavage furrow

25
Q

Look

A
26
Q

What is the significance of mitosis

A

Growth, repair and asexual reproduction
Animal - blood and skin cells are constantly replaced
Plant - root and shoot tip meristems constantly undergo mitosis

27
Q

What is a proto-oncogene?

A

Gene that has the potential to cause cancer

28
Q

Describe the cell division which leads to the formation of tumours and cancers

A

Uncontrollable

29
Q

How does vincristine help treat cancer

A
  • prevents formation of spindle so arresting mitosis at metaphase
  • slows the rate of cell division
30
Q

Define meiosis

A

Two consecutive cell divisions to produce four genetically different, haploid cells

31
Q

Where does meiosis occur

A

Gametes

32
Q

When does interphase occur during meiosis

A

Before prophase 1

33
Q

Look

A
34
Q

What increases genetic variation during meiosis

A

Bivalents crossing over

Independent assortment

35
Q

What happens during prophase 1 meiosis

A
  • Chromosomes condense to become shorter and thicker
  • Centrioles move to opposite poles (not higher plants)
  • Chromosomes come together in homologous pairs (bivalent)
  • Crossing over occurs - part of one chromatid is exchanged with another
  • Nucleolus and nuclear membrane disappear
36
Q

DNA content and chromosome number per cell during prophase 1

A

2

2n

37
Q

What happens during metaphase 1

A

• Spindle forms
• Homologous chromosome pairs (bivalents) align at the equator of the cell attached to spindle microtubules via centromere
• This alignment is random and called
independent assortment

38
Q

DNA content and chromosome number per cell metaphase 1

A

4

2n

39
Q

What happens during anaphase 1

A
  • Spindle fires shorten

* Bivalents separate and chromosomes are pulled towards opposite poles

40
Q

DNA content and chromosome number per cell in anaphase 1

A

4

2n

41
Q

What happens during telophase 1

A

Chromosomes reach poles

42
Q

DNA content and chromosome number per cell in telophase 1

A

4

2n

43
Q

Cytokinesis of meiosis 1

A

Division of cytoplasm

2 haploid cells

44
Q

What happens during prophase 2

A

Centrioles separate, and arrange

themselves at 90° to the previous spindle

45
Q

DNA content and chromosome number per cell in prophase 2

A

2

n

46
Q

What happens during metaphase 2

A

Chromosomes align at the equator of the cell attached to spindle microtubules via centromere

47
Q

DNA content and chromosome number per cell in metaphase 2

A

2

n

48
Q

What happens during anaphase 2

A
  • Spindle fires shorten

* Centromeres divide, and chromatids are pulled towards opposite poles

49
Q

DNA content and chromosome number per cell in anaphase 2

A

2

n

50
Q

What happens during telophase 2

A 
• Chromatids reach poles and become
indistinct
• Nuclear envelope reforms
• Nucleolus reforms
• Spindle disintegrates
51
Q

DNA content and chromosome number per cell in telophase 2

A

2

n

52
Q

Cytokinesis meiosis 2

A

Four haploid cells produced

53
Q

DNA content and chromosome number per cell in cytokinesis of meiosis 2

A

1

n

54
Q

DNA content and chromosome number per cell in cytokinesis of meiosis 1

A

2

n

55
Q

What is the significance of meiosis

A
  • genetic variation- crossing over and independent assortment
  • keeps constant chromosome number - gametes recombine during fertilisation which restores diploid number

Wjec Biology As Unit 1 (7 decks)

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