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Biology 1000 > Unit 8-Cell Division > Flashcards

Unit 8-Cell Division Flashcards

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1
Q

Define cell division

A

Reproduction of a cell that results in two daughter cells that are genetically identical to each other and to the original parent cell

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2
Q

What are chromosomes

A

The structures that contain most of the cells DNA

It is split into two during cell division.

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3
Q

Define asexual reproduction

A

The creation of genetically identical offspring by a single parent without the participation of sperm and egg

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4
Q

Define sexual reproduction

A

It requires fertilization of an egg by a sperm
The production of gametes involves a special type of cell division that occurs only in reproductive organs
Offspring resemble parents but not identical

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5
Q

Define mitosis

A

One mother cell producing two daughter cells
Genetically identical
Same number of chromosomes
Happens in all eukaryotes

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6
Q

Define meiosis

A 
One mother cell divides into 4 products 
Genetically unique 
Half as many chromosomes
Happens only in specialized structures of certain eukaryotes 
Produces spores eggs or sperm
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7
Q

What are the three functions of cell division

A

Reproduction
Growth
Repair

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8
Q

Explain DNA organization

A

Chromosomes (X)
The coiled fibres are chromatin
DNA is wrapped around a Histone

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9
Q

How do prokaryotes reproduce

A

Binary fission

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10
Q

What is binary fission

What type of reproduction is it

A

Cell divides in half

Asexual

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11
Q

What are sister chromatids and what are they held together by

A

Duplicated chromosomes which contain identical copies of the DNA molecule
Held together by the centromere

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12
Q

When does a chromosome consist of two identical chromatids

A

When the cell is preparing to divide and has duplicated its chromosomes but before the duplicates actually separate

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13
Q

Explain the cell cycle

A

An ordered sequence of events that extends from the time a cell is first formed from a dividing parent cell until its own division into two cells

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14
Q

How is the DNA packaged in a working cell (interphase)

A

Chromatin

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15
Q

How is DNA packaged during cell division (M phase)

A

Chromosomes

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16
Q

Define interphase

A 
What most of the cell cycle consists of 
Cells metabolic activity is high and the cell preforms various functions 
Periods of growth
DNA replication
Preparation for mitosis
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17
Q

Define the mitotic phase (M phase)

A

The part of the cell cycle when the cell actually divides

Nuclear division

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18
Q

Define cytokinesis

A

Begins before mitosis ends
The cytoplasm is divided in two
Cell division

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19
Q

Explain the stages of interphase

A

G1
-organelle expansion and cell growth
S phase
- DNA synthesis when chromosomes duplicate
G2
- mitochondria and chloroplasts growth centrosome divides
G0
- typical cell functions; respiration working and moving

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20
Q

What do we start with in mitosis

A

One cell with one nucleus

Two copies of each chromosome (chromatids)

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21
Q

What do we end with in mitosis

A

Two nuclei

Each with one copy of each chromosome

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22
Q

Where are the chromosomes during mitosis

A

In the nucleus

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23
Q

Where are the centrosomes during mitosis

A

In cytoplasm

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24
Q

Explain prophase

A

The chromatin fibres become more tightly coiled into chromosomes as sister chromatids
The mitotic spindles begins to form from the centrosomes
Centrosomes move away from each other

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25
Q

Explain pro-metaphase

A

The nuclear envelop breaks into fragments and disappears
Microtubules and centrosomes move to opposite poles and the mitotic spindles reach for the chromosomes
Mitotic spindles attach to kinetochore

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26
Q

Explain metaphase

A

Mitotic spindles are attached to chromosomes and they are moved to the centre or metaphase plate

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27
Q

Explain anaphase

A

The two centromeres of each chromosome come apart separating the sister chromatids
Move to each pole with an equivalent and complete set of chromosomes

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28
Q

Explain telophase

A

The cell continues to elongates
Daughter nuclei appear at the two poles
Nuclear envelope begins to form around chromosomes
Chromatin uncoils from the chromosome shape and mitotic spindles disappear

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29
Q

Explain cytokinesis

A

The division of the cytoplasm

When the two daughter cells completely separate

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30
Q

Define the cleavage furrow

A

A shallow indentation in the cell surface

Happens in animal cells

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31
Q

Define cell plate

A

A membranous disc
Grows outward
Happens in plants

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32
Q

What happens when cytokinesis doesn’t occur

A

Results in a bigger cell with two identical nuclei

Yellow slime mould and muscle cells- lives as large multinuclei complexes

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33
Q

Define syncytium

A

Organisms that live as a very large cell containing multiple nuclei

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34
Q

Define the cell cycle control system

A

A cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle

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35
Q

Checkpoints in cell cycles

A

A critical control point where stop and go signals can regulate the cycle

36
Q

What checkpoint in the cell cycle is seen as the most important

A

G1 checkpoint
Because if given go ahead it goes into cell division stages but if not then it goes into G0 where the cell doesn’t divide

37
Q

What are the requirements of the G1 checkpoint

A

Is the cell large enough
Does the cell have enough nutrients
Is the DNA undamaged
Have the growth factors signalled

38
Q

What are the requirements of the G2 checkpoint

A

Before the M phase

Must have successful DNA replication and undamaged DNA

39
Q

What are the requirements of the metaphase checkpoint

A

Happens before anaphase

Spindle fibres have to attach and ensure equal distribution

40
Q

What is a tumour

A

An abnormally growing mass of body cells

41
Q

Define benign tumours

A

When abnormal cells remain at the original site (are contained)
Can cause problems if they grow in and disrupt certain organs

42
Q

Define malignant tumours

A

Can spread into neighbouring tissues (cancerous)

43
Q

Define metastasis

A

The spread of cancer cells beyond their original site

44
Q

How are chromosomes arranged in meiosis

A

As homologous pairs

45
Q

Define homologous pairs

A

Two matching chromosomes

Same genes but maybe in different forms

46
Q

Define the locus

A

The particular place a gene is located to code for a specific trait such as freckles and is found on the chromosome

47
Q

How many chromosomes in humans

How many pairs of chromosomes in humans

A

46

23

48
Q

Are all of your chromosomes fully homologous

A

If you are a female then yes

If you are a male then no
- your sex chromosomes are only partly homologous

49
Q

Define sex chromosomes

Define autosomes

A

The chromosomes that determines an individuals sex

The other 22 pairs of chromosomes are called autosomes

50
Q

Define somatic cells

A

Body cells

51
Q

Are somatic cells diploid or haploid

A

Diploid cells 2N
Two complete sets
Homologous pairs
Two copies of each gene

52
Q

Are sex cells haploid or diploid

A

Haploid 1N
Half as many chromosomes
One copy of each gene

53
Q

A fertilized egg is called what

A

A zygote

54
Q

Is a zygote haploid or diploid

A

Diploid
Has two sets of chromosomes
One set from each parent

55
Q

Define meiosis

A

A type of cell division that produces haploid cells in diploid organisms
If it weren’t for meiosis each generation would have twice as much genetic material as the generation before

56
Q

explain interphase during meiosis

A

similar to mitosis; at the end of interphase each chromosome consists of two genetically identical sister chromatids and the centrosome also duplicates

57
Q

explain prophase 1

A

chromatin coils up to form chromosomes
synapsis occurs which is when homologous chromosomes come together into pairs which is called a tetrad
crossing over occurs
centromeres move apart spindle fibres produce and nuclear envelope dissolves

58
Q

explain metaphase 1

A

chromosome tetrads align in the center

homologous chromosomes are linked together by crossing over

59
Q

explain anaphase 1

A

the chromosomes move towards the two poles

the sister chromatids stick together and only the homologous chromosomes split and move across

60
Q

explain telophase 1

A

the chromosomes arrive at the opposite ends and still consist of two sister chromatids

61
Q

explain cytokinesis after telophase 1

A

usually cytokinesis occurs after telophase 1 and two haploid daughter cells are formed
sometimes the chromosomes uncoil and the nuclear envelop reforms

62
Q

is there a interphase after meiosis 1

A

in some yes in others daughter cells produced divide immediately
in either case NO chromosome duplication occurs between telophase 1 and the beginning of meiosis 2

63
Q

explain prophase 2

A

a spindle fibre forms and moves the chromosomes toward the middle

64
Q

explain metaphase 2

A

the chromosomes align at the middle and begin to be pulled to the opposite sides

65
Q

explain anaphase 2

A

the centromeres of sister chromatids finally separate and the sister chromatids of each pair are now individual daughter chromosomes and move to opposite sides of the poles

66
Q

explain telophase 2

A

nuclei form at the cell poles and cytokinesis begins as well

67
Q

after meiosis 2 what are the results

A

four daughter cells each with the haploid number of (single) chromosomes

68
Q

is meiosis 2 the same as mitosis

A

basically yes

69
Q

a cell has the haploid number of chromosomes but each chromosome has two chromatids. the chromosomes are arranged singly at the center of the spindle. what is the meiotic stage

A

metaphase 2

70
Q

what do we start with in meiosis

A

one cell with one nucleus

two copies of each homologous pair of chromosome (tetrad)

71
Q

what do we end with in meiosis

A

four cells

each with one copy of one of the homologous chromosomes

72
Q

where are the chromosomes during meiosis

A

the nucleus

73
Q

where are the centrosomes during meiosis

A

the cytoplasm

74
Q

compare mitosis and meiosis - DNA replication

A

for both mitosis and meiosis the chromosomes duplicate only once during S phase

75
Q

compare mitosis and meiosis - number of cell divisions

A

mitosis- one division of the nucleus

meiosis - two nuclear and cytoplasmic divisions

76
Q

compare mitosis and meiosis - products

A

Mitosis - produces two identical diploid cells

meiosis - produces four haploid cells

77
Q

define crossing over

A

an exchange of corresponding segments between non-sister chromatids of homologous chromosomes

78
Q

what is a chiasma

A

the place where two homologous chromatids are attached to each other

79
Q

define genetic recombination

A

the production of gene combinations different from those carried by the original parental chromosome

80
Q

what is a karyotype

A

a photographic inventory of an individuals chromosomes

an ordered display of magnified images of an individuals chromosomes arranged in pairs

81
Q

what is trisomy 21

A

an extra copy of chromosome 21 that causes down syndrome

82
Q

what is nondisjunction

A

an occasional mishap in which the members of a chromosome pair fail to separate

83
Q

explain how nondisjunction could result in a diploid gamete

A

a diploid gamete would result if the nondisjunction affected all the chromosomes during one of the meiotic divisions

84
Q

Animal life cycle

A

Start with a diploid(somatic cells)multicellular animal

Gamete production

  • by meiosis
  • occurs within gonads
  • produces haploid cells (sperm and egg)

Fertilization
- forms a diploid zygote

85
Q

Fungus life cycle

A

Starts with multicellular fungus
The haploid structure grows from the spores

Gamete production

  • by mitosis
  • produces single haploid cells

Fertilization

  • forms a diploid zygote
  • then divides by meiosis which forms haploid spores
86
Q

Plant life cycle

A

Starts with multicellular plant that is diploid

Produces haploid spores by meiosis

Spores germinate creating a haploid multicellular plant

Produces haploid gametes by mitosis

Fertilization creates a diploid zygote

Biology 1000 (11 decks)

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