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topic 6 cell division Flashcards

1
Q

cell cycle s 3 main phases

A

-interphase
-mitosis
-cytokenisis

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2
Q

interphases 3 phases

A

-G1 phase - cell grows and makes new proteins to replicate organelles
-S phase - dna is replicates
-G2 phase - cell continues to grow and replixated DNA is checked for
if any chromosomes r damaged during G2

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3
Q

at what stage in interphase does the cell replace its energy store

A

s phase

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4
Q

2 parts of mitotic phase

A

mitosis- where chromosomes r seperated into 2 nuclei
cytokenisis- where cell divides into 2

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5
Q

what stage does the cell enter if exits the cycle

A

G0

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6
Q

ehy does a cell enter G0

A
  • if the cell is fully differntiated
    -Dna is damaged out a certain point the cell is no longer able to divide when this happens the cell is called senscent cells
  • some cells enter g0 temporarily these cells can then be triggered to reenter the cell cycle during an infection
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7
Q

3 checkpoints

A

G1 checkpoint- checks cell has chemicals needed for replication and damage to DNA and if cell has grown to correct size
G2 checkpoint- checks DNA has been replicated without any errors if the cell does it tries to repair them. checks for dna damage and cell had grown to correct size
Metaphase checkpoint- each chromosome checked to ensure they are assembled correctly on mitotic spindle

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8
Q

what happens if a cell fails a checkpoint

A

enters G0

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9
Q

what are chromosomes

A

structures located inside the nucleus of animal and plant cells consisting of DNA tightly coiled around proteins called histones

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10
Q

How many chromosomes do humans have?

A
  1. Chromosome divided into 23 pairs.
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11
Q

What are the first 22 pairs of chromosomes called

A

autosomes (identical in both males and females)

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12
Q

what is the 23rd pair known as?

A

Sex chromosome

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13
Q

what are the two chromatids in each chromosome held together by?

A

centromere

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14
Q

How many pairs of chromosomes do diploid cells have?

A

Two copies of each chromosome one from each parent

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15
Q

What is the total number of chromosomes in a diploid cell described as?

A

2n

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16
Q

How many copies of each chromosome do haploid cells carry?

A

One copy of each chromosome

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17
Q

what is the total number of chromosomes in a haploid cell described as?

A

n

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18
Q

Once cells have completed interphase, what do they undergo

A

Mitosis and cytokinesis

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19
Q

what takes place during the end phase ( mitotic phase )

A

Cytokinesis and mitosis

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20
Q

mitosis is used by organisms for many processes, including

A

Growth
Replacement of damaged or dead tissues
Asexual reproduction
development of body plans
Production of stem cells

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21
Q

can we see chromosomes in interphase?

A

No, as they are in the nucleus as chromatin so they have a loose open structure

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22
Q

Four stages of mitosis

A

prophase
Metaphase
Anaphase
Telophase

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23
Q

Prophase (mitosis)

A

The chromosomes condense
A pair of centrioles migrate to opposite poles of the cell
Each centriole starts forming spindle fibers which attach the centromere of each chromosome
Spindle fibers start to move the chromosomes towards the center of the cell
Nucleus disappears a nuclear envelope starts to break down so chromosomes are free in cytoplasm

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24
Q

Metaphase (mitosis)

A

chromosomes lineup at equator
Spindle apparatus has completely formed
each chromosome attaches to the spindle by their centromere
At metaphase checkpoint each chromosome is checked to ensure it is attached to spindle

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25
anaphase (mitosis)
centromeres divide to separate each pair of sister chromatids Spindle fibers contraction shorten to pull the chromatids to opposite poles of cell Each chromatid is pulled by centromere, causing them to take a V shape
26
Telephase (mitosis)
The chromatics reached the opposite poles of the cell, where they uncoil to become their chromatin state Spindle or part of breaks down and nuclear envelope forms around each set of chromosomes to form two nuclei and nucleolus starts to reform
27
Cytokinesis
produces two daughter cells that are genetically identical Central cell membrane is pulled inwards by cytoskeleton. This creates a groove which gradually deepens eventually the membranes fuse to form two independent cells.
28
Mitosis and cytokinesis in plant cells
centrioles do not play a role in forming the spindle apparatus bcs they dont have centrioles when they undergo cytokenisis vesicles from the golgi apparatus form membrane structures down the center of the cell instead ,these then fuse together to form a central cell membrane. a new cellulose wall forms
29
meiosis
a type of cell division in which a parent cell which is diploid divides to form 4 haploid cells each genetically distinct from eachother
30
where does meiosis only take place
sex organs
31
the 2 divisions cells undergo in meiosis
-meiosis I - homologous chromosomes are seperated -meiosis II - sister chromatids are seperated
32
reduction division
where the chromosome number is halved to form haploid cells
33
before meiosis starts what happens first
dna is replicated during interphase so each chromosome contains two chromatids
34
prophase I
-chromosomes condense to become visible and homologous chromosomes link together to form chiasmata -crossing over takes place -centrioles migrate to opposite poles of the cell and starts forming spindle fibres -nucleolus disappears and nuclear envelope starts to break down leaving chromosomes free in cytoplasm
35
metaphase I
-pairs of homologous chromsomes libe up along the eqator -spindle fibres attaches to chromosomes centromere
36
anaphase I
-spindle fbres shorten and homologous pairs are seperated and pulled to opposite poles -for this to happen the chiasmata between the homologous chromosomes break
37
telophase I
-chromosomes reach the opposite poles of the cell where they uncoil -nuclear envelope forms around each set of chromosomes and nucleolus starts to reform
38
what happens after telophase I
cytokenisis
39
prophase II
-centrioles migrate to opposite ends of the cell and start forming spindle fibres -nucleolus disappears and nuclear envelope starts to break down
40
metaphase II
-chromosomes line up at equator -each chromosome attaches to the spindle fibres by their cetromere
41
anaphase II
-centromeres divide and seperate each pair of chromatids -spindle fibres contract and shorten to pull the chromatids to opposite poles of the cell
42
telophase II
-chromosomes reach opposite poles of the cell where they uncoil -nuclear envelope forms around each set of chromsomes to form two nuclei and the nucleolus starts to reform
43
what does meiosis produce
4 genetically different haploid cells
44
why is the type of cell division meiosis involves important
-production of gametes which allow sexual reproduction to take place -creates genetic variation increasing diversity and allowing natural selection to take place
45
what events in meiosis lead to genetic variation
-crossing over (recombination) -independent segregation (random assortment) random fusion of gametes also but not during meiosis
46
in what stage of meiosis does crossing over occur
prophase I
47
steps of crossing over
-homologous chromosomes condense and pair up - homologous pair come together and the chromatids of the chromosomes wrap around each other -parts of the chromatids can break off and exchange between the homologous chromosomes -when tje chromosomes are seperated the chromosomes break at the chiasmata and alleles are swapped
48
chiasmata
where the chromatids are joined during crossing over
49
abivalent
attached pair of chromsomes during crossing over
50
recombinant chromosomes
chromosomes that have exchanged dna and so can exchange alleles
51
why is crossing over a major source of genetic variation in meiosis
chiasmata can form at multiple points
52
independent segregation (random assortment)
when the chromosomes line up along the cells equator whether the paternal or maternal chromosomes appear on left or right is completely random
53
formula to calculate the number of genetically different zygotes that are possible from two parents
(2^n)^2 n is the number of chromosomes
54
how to calculate the number of genetically distinct gametes produced as a result of independent segregation
2^n
55
specialised cells
cells with certain features that allow them to carry out a particular function
56
tissues
a group of similar cells working together to carry out a particular function
57
organ
a group of organs working together to carry out a particular function
58
levels of organisation
specialised cells tissues organs organ system
59
squamous epithilieum tissue
-provide long thin lining for many organs such as the lungs -made up of a single layer of squamous ciliated epithilial cells
60
ciliated epithelium tissue
lines organs such as the trachea where it can sweep mucus away from the lungs -made up of ciliated epithilial cells and goblet cells
61
cartilage tissue
type of connective tissue that acts as a cushion between bones and also provides support to organs such as the ears and nose -made up of chondrocyte cells fixed with an extracellular matrix
62
muscle tissue
made up ofmuscle fibres which contract and relax to move different parts of the body three types of muscle tissue -smooth- found in the walls of organs -cardiac- found in the heart -skeletal- found attached to bones
63
xylem tissue
responsible for thetransport of water and minerals within plants -made up of dead xylem vessle cells which have no ends so water can flow and no organelles walls are strengthened by lignin
64
pholem
responsible for the transport of sugars and amino acids within plants -made up of columns of sieve tube elements and companion cells -seieve plates sepereate seive tube elements with holes -companion cells contain lots of mitochondria
65
erythrocytes and its specialised features
-responsible for transporting oxygen around the body *flattened biconcave shape *no nucleus or organelles *flexible
66
neutrophils and its specialised features
type of white blood cell that help to defend the body against pathogens *flexible cell membrane *contain many lysosmes *multi lobed nucleus
67
sperm cells and its specialised features
carry genetic info to female gamete *flagellum *many mitochondria *acrosome containing
68
squamous epithelial cells and its specialised features
cover the surface of organs such as the lungs and blood vessles *very thin *permeable
69
ciliated epithelial cells and its specialised features
cover the surface of organs where they can move substances such as mucus or egg cells *cilia
70
palisade cells and its specialised features
-carry out photosynthesis in the leaves of a plant *lots of chloroplasts *thin cell walls *tall and thin shape
71
root hair cells and its specialised features
absorb water and mineral ions from the soil * root hair structures * thin permeable cell wall * lots of mitochondria
72
guard cells and its specialised features
control the opening and closing of stomata * come in pairs * change shape when light is present * change shape when the lose water * thin outer walls and thicker inner walls
73
stem cells
undifferentiated cells that can develop into other types of cells
74
what are stem cells used for by organisms
growth, development and tissue repair
75
two key features of stem cells
-can divide by mitosis to produce more undifferentiated cells -can differentiate into specialised cells
76
what are stem cells grouped on based off of
their ability to differentiate (potency)
77
totipotent stem cells
these differentiate into any cell type and go on to form whole organisms
78
pluripotent stem cells
these can differentiate into most cell types but cannot form whole organisms
79
multipotent stem cells
these can only differentiate into a few different cell types
80
unipotent stem cell
these can only differentiate into one type of cell
81
embryonic stem cells
-found in early stages of embryo development where they can differentiate into cells to forma foetus -in the first few divisions the stem cells are totipotent but after 7 days are pluripotent
82
adult stem cells
-found in some adult tissues where they can replace faulty cells -stem cells are multipotent or unipotent -stem cells in the bone marrow replace worn out erythrocytes and neutrophils
83
plant stem cells
-found in meristematic tissues or meristems -pluripotent -meristematic tissue is found between pholem and xylem tissues in an area known as the vascular cambium which differentiate into cells of the xylem and pholem
84
stem cells can be used for
-treat certain diseases by replacing faulty cells -testing new drugs -studying the development of organisms -identifying causes of disorders

Biology (8 decks)

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