Cell Division, Cell Diversity And Cell Differentation Flashcards
(206 cards)
1
Q
What could early researchers observing cell division under microscopes easily see?
A
Mitosis
2
Q
What is mitosis
A
Nuclear division followed by cytokinesis/ cytoplasmic division resulting in two daughter cells
3
Q
What’s the M phase?
A
Nuclear and cytoplasmic division.
4
Q
What much of the cell cycle is occupied by the M phase?
A
Only a small part
5
Q
What is between each M phase?
A
Interphase
6
Q
What happens in interphase observed under a microscope?
A
Not much
7
Q
What has allowed change from this belief on interphase?
A
More sophicated techniques
8
Q
What do scientists now believe happens in interphase?
A
Elaborate preparations being made for cell division
This is carefully ordered and controlled sequence with checkpoints
9
Q
What are the two main cell cycle checkpoints?
A
G1/ S checkpoint
G2/ M checkpoint
10
Q
Are there other checkpoint other than these two during interphase?
A
Yes
11
Q
Give two example of where another one is?
A
Halfway through mitosis
In early G1
12
Q
What are the functions of checkpoints?
A
To prevent cancer
To detect and repair damage to DNA
13
Q
How can a checkpoint prevent cancer?
A
By preventing uncontrolled cell division which would lead to a tumour
14
Q
Give an example of where the cell may repair damage to DNA?
A
Damage caused by UV light
15
Q
What causes the cell cycle to happen in a certain sequence?
A
Molecular events
16
Q
What else do these molecular events control?
A
Cell can’t be reversed
DNA only duplicated once during cell cycle
17
Q
Name the five main phases of the cell cycle?
A
M phase G0 phase G1 phase S phase G2 phase
18
Q
In the M phase, what does A checkpoint chemical trigger?
A
Condensation of chromatin
19
Q
What checkpoint happens halfway through the M phase?
A
The metaphase checkpoint which ensured that the cell is ready to complete mitosis
20
Q
What events happen in the M phase within the cell?
A
Cell growth stops
Nuclear division (mitosis) consisting of four stages
Cytokinesis
21
Q
What are the four stages if nuclear division?
A
Prophase, metaphase, anaphase and telophase
22
Q
What is cytokinesis?
A
Cytoplasmic division
23
Q
What is G0 really called?
A
Gap 0 phase
24
Q
What sort of phase is gap 0?
A
A resting phase
25
What triggers Gap 0 phase?
A checkpoint chemical in early G1
26
Do all cells have gap 0 phase?
No some cell din such as epithelial cells lining the gut
27
What may cells in gap 0 go under?
Apoptosis, differentiation or senescence
28
What's apoptosis?
Programmed cell death
29
How long will some cells stay in gap 0?
Very long time or indefinitely
30
What is G1 phase called?
Gap 1 phase
| Growth phase
31
What a G1 checkpoint control mechanism does what?
Ensures the cell is ready to enter the S phase and begin DNA synthesis
32
What 5 events happens in gap 1 phase?
```
Cells grow and increase in size
Transcription of genes to make RNA occurs
Organelles duplicate
Biosynthesis
The p53 gene helps control this phase
```
33
Give a example of biosynthesis that happens?
Protein synthesis including making enzymes needed for DNA
34
What is the p53 gene?
The rumour suppressor
35
What is the S phase really called?
Synthesis phase
36
Why is every molecules of DNA replicated during the synthesis phase?
Chromosomes are unwound and DNA will diffuse
37
Is there a specific sequence to the replication of DNA in synthesis phase?
Yes
38
What types of cells are duplicated first in the synthesis stage?
Housekeeping genes
39
What do housekeeping genes do?
Active in all types of cells
40
What types of cells are duplicated last in the synthesis stage of interphase?
Genes that are normally inactive in specific types of cells
41
Once the cell has entered the synthesis phase of interphase it is?
Committed to completing the cell cycle
42
What events happen in synthesis phase of interphase?
DNA replicates
43
What happens when all chromosomes have been duplicated in the synthesis phase?
Each one consists of a pair of identical sister chromatids
44
What speed is synthesis phase and why?
Rapid because exposed DNA base pairs are more susceptible to mutagenic agents reduces chances of spontaneous mutations happening
45
What is the real name of G2?
Gap 2 phase
46
What do special chemicals in gap 2 phase ensure?
Cells are ready for mitosis by stimulating proteins that will be involved in making chromosomes condense and in formation of the spindle
47
What events happen during gap 2 phase?
Cells grow
48
How do cells reproduce?
Duplicating their contents and then splitting into two daughter cells
49
Is there an infinite amount of times cells should undergo cell division?
Yes there is normally only a certain number of cycles
50
What is the number of cycles cells should undergo called?
Hayflick constant
51
What is hayflick constant?
About 50
52
What happens if cell division becomes uncontrolled?
A tumour can form which may become malignant or cancerous
53
What do Porto-oncogenes ?
Help regulate cell division by coding for proteins that help regulate cell growth and differentiation.
54
What happens if these proto-oncogenes mutate?
They may become oncogenes and cause cells to fail to undergo apoptosis and keep dividing causing a tumour
55
Why is P53 important?
It triggers two major checkpoints in the regulation of the cell cycle
56
What is p53 gene also known as?
Tumour suppressor gene
57
Name other regulatory protein?
Cyclins
| CDK's
58
What are cylins?
Synthesised response to cell-signalling molecules such as growth factors
59
Why did the scientist call it cylin?
For love of cycling but title is appropriate
60
What are CDK's?
Cylin-dependent kinases
61
How does the prokaryotic cell cycle occur?
By binary fission
62
What basically happens in binary fission?
Cells grow to its limit of size and then splits into two.
63
What happens in binary fission before the cell divides?
The DNA is replicated
64
What happens in binary fission after The DNA is replicated?
Two new loops of DNA are pulled to opposite ends of the cell and a cell wall forms which begin to separate the bacterial cell.
65
What does each new cell from binary fission contain?
Replicated plasmids and synthesised ribosomes
66
How do microchrondria and chloroplasts divide?
By binary fission
67
Why do living organisms need to produce genetically identical daughter cells by mitosis?
Assexual reproduction
Growth
Tissue repair
68
What uses asexual reproduction?
```
Single-celled protoctists such as amoeba and paramecium
Some plants
Fungi
Rarer in animals
Aphids can
```
69
Who uses growth via mitosis?
All multicellular organisms that are genetically identical to each other and to patent cells from which they arose
70
Tissue repair?
Wounds heal when growth factors secret platelets and macrophages and damaged cells of the blood-vessel walls stimulate proliferation of endothelial and smooth muscle cell to pair damaged blood vessels.
71
Does mitosis ever stop?
No its continuous
72
What are the four stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
73
What happens in prophase to the chromosomes replicated in the s phase?
Chromosomes replicated during the s phase of interphase and consists of 2 identical sister chromatids shortened and thickened as DNA supercoils.
74
What does the nuclear envelope do?
Break down
75
What do the centriole in animal cells (usually centromere) do in prophase?
Divides and the two new daughter centrioles move to opposite poles of the cell
76
What does the cytoskeleton do in the prophase?
Tumbling threads form a spindle between these centrioles. In plant cells the tublin threads are formed
77
In metaphase what happens?
Pairs of chromatids attach to spindle threads by their centromeres at equator region
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What happens in anaphase (centromere)?
Centromeres of each pair of chromatids spilt.
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What happens in anaphase (motor protein)?
Motor proteins walking along tublin threads pull each sister chromatid of a pair in the opposite direction towards the opposite pole.
80
What happens in anaphase (V shape)?
Chromatids (chromosomes) assume V shape
81
What happens to the chromosomes in telophase?
Separated chromosomes teach the poles
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What also happens each set of chromosomes?
A new nuclear envelope forms
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What does the cell now contain in telophase?
Two genetically identical nuclei
84
What happens when mitosis is complete?
Cell splits in two so that each cell contains a nucleus
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What happens to the plasma membrane in animal cells in cytokinesis?
Folds inwards and nips in the cytoplasm
86
What happens to the plasma membrane in plant cells in cytokinesis?
An end plate forms where the equator of the spindle was and new plasma membrane and cellulose cell- wall material are laid down on either side along this end plate
87
What are formed from cytokinesis?
2 new daughter cells now formed which are genetically identical to each other and to the parent cell.
88
How does sexual reproduction increase genetic variation?
It involves combining of Genetic material from two unrelated individuals of the same species by fertilisation.
89
What does genetic variation within a population increase chances of?
Survival when the environment changes as some individuals will have characteristics enabling them to be better adapted to the change.
90
What are body cells in many organisms?
Diploid
91
What type of cell must sexual reproduction use?
Haploid gametes
92
Why must it be haploid for sexual reproduction?
When two gamete nuclei fuse during fertilisation a diploid zygote is produced and the normal chromosomes number is maintained through the generation
93
Where does meiosis occur?
In diploid germ cells in gonads to produce haploid gametes
94
What are gonads?
Ovaries and testes
95
How many chromosomes in body cell?
46
96
How many chromosomes from each parent?
23 from mother egg nucleus , 23 from father sperm nucleus
97
What can these chromosomes do?
Form matching pairs one maternal and one paternal chromosomes containing same genes at the same places on the chromosomes
98
What are these matching pairs called?
Homologous chromosomes
99
What even though they have the same genes have different?
Alleles
100
What happens before meiosis?
S phase of interphase
101
What happens in S phase of interphase (meiosis)?
Each chromosomes are duplicated as its DNA replicated after which each chromosomes consists of two sister chromatids.
102
What happens in meiosis?
Chromosomes pair up in their homologous pairs
103
How many divisions in meiosis?
2
104
How many phases in each division of meiosis?
4
105
What are the names of all the phases in the first and second phase of meiosis?
Prophase 1, metaphase 1, anaphase 1, telophase 1
| Prophase 2, metaphase 2, anaphase 2, telophase 2
106
What do the cells do between first and second division?
A short interphase
107
Where does the second division happen?
Place in a plane at right angles to that if meiosis 1.
108
What happens after the second division?
Cytokinesis
109
In prophase 1, what does chromatin do?
Condense and each chromosome supercoils. In this state it can take yo stains and can be seen with light microscope
110
During prophase 1, what does the nuclear envelope do?
The nuclear envelope breaks down and spindle threads of tublin protein form from the centriole in animal cells.
111
Can the chromosomes come together in their homologous pairs in prophase 1?
Yes
112
What does each chromosome consist of prophase 1?
Two chromatids
113
Where does crossing over occur in prophase 1?
Where non-sister chromatids wrap around each other and may swap sections so that alleles are shuffled
114
Metaphase 1: what do the pairs of homologous chromosomes do?
Attach along equator of spindle, each attach to spindle thread by its centromere,
115
Metaphase 1: how are homologous pairs arranged?
Randomly with members of each pair factions opposite poles of the cell. Arrangement is independent assortment.
116
What does the way they line up in metaphase 1 determine?
How they will segregate independently when pulled apart during anaphase
117
What do motor proteins do in anaphase 1?
Pull members of each pair of homologous chromosomes apart and drag them along the tublin threads of the spindle
118
What don't the centromeres do in anaphase 1?
Divide and each chromosomes consists of two chromatids.
119
What does the crossed-over area do in anaphase 1?
Separate from each other resulting in swapped areas of chromosomes and allele shuffling.
120
What do animal cells do in telophase 1?
Have 2 new nuclear envelopes form around each set of chromosomes and the cell divides by cytokinesis. Short interphase where chromosomes uncoil follows.
121
What does each new nucleus contain telophase 1?
Each new nucleus contains half the original number of chromosomes but each chromosome consists of 2 chromatids.
122
What happens in telophase 1?
Cell goes straight from anaphase 1 to prophase 2
123
Prophase 2 nuclear envelopes do what?
If they have reformed they will break died
124
What do the chromosomes do in prophase 2?
Chromosomes coil and condense each one consisting of two chromatids. Chromatids of each chromosome no longer identical to crossing over in prophase 1.
125
What do spindles do in prophase 2?
Form
126
What do chromosomes do in metaphase 2?
Attach by their centromere to the equator of the spindle
127
How are the chromatids arranged and what does determine?
Randomly arranged
| the way they are arranged will determine how the chromatic separate during anaphase
128
During anaphase 2 what do centromeres do?
Divide
129
What do chromatids of each chromosome do in anaphase 2?
Get pulled apart by motor proteins that drag then along the tublin threads if the spindle towards the poles. Therefore they are randomly segregated.
130
What does telophase 2 nuclear envelopes do?
Form around each of the four haploid nucleus
131
In telophase what happens in animals?
Two cells now divide to give four haploid cells.
132
In telophase what happens in plants?
Tetrad of four haploid cells is formed.
133
How does meiosis produce genetic variation?
Crossing over during prophase 1 shuffles alleles
Independent assortment of chromosomes in anaphase 1 leads to random distribution of maternal and paternal chromosomes of each pair
Independent assortment of chromatids in anaphase 2 leads to further random distribution of genetic material
Haploid gametes are produce which can undergo random fusion with gametes derived from another organism of the same species
134
What is the division of labour within a single-celled organism determined by?
Organelles which each have a specific function
135
Single celled organism are small therefore:
They have a large surface area to volume ratio so oxygen can diffuse across plasma membrane and waste products can diffuse out via the same membrane.
136
Multicellular organisms are bigger therefore:
Smaller surface area to volume ratio which means that most cells don't have contact with external environment so need specialised cells to carry out particular functions.
137
How do multicellular organisms start out life?
As a single undifferentiated cell (zygote)
138
How does a zygote happen?
Ovum is fertilised by a spermatozoon and two haploid nuclei fuse to give a cell with a diploid nucleus
139
Is a zygote specialised?
No
140
What genes are therefore turned on in a zygote?
All of the ones in its genome
141
What type of cell is a zygote and how can it divide?
Divide by mitosis
| A stem cell
142
What happens after several motor of divisions?
An embryo forms containing many undifferentiated embryonic stem cells
143
When do these embryonic cells differentiate?
As certain genes are switched off and other genes may be expressed more
144
How do the differentiated cells now differ?
Proportions of different organelles differs from those of other cells
Shape of cell change
Some of contents if the cell change
145
What causes each cell type to specialised for a particular function?
Differentiation
146
What do erythrocytes do?
Carry oxygen from lungs to respiring cells
147
What do neutrophils do?
Ingest invading pathogens
148
What do erythrocytes and neutrophils derive from?
Stem cells in bone marrow
149
How are erythrocytes adapted to carry out their function
Very small
Flexible
Most of their organelles lost at differentiation
Biconcave
150
What does being very small mean for erythrocytes adaptions?
They are about 7.5 um in diameter
Large surface area to volume ratio
Oxygen can easily diffuse across cell
151
What does being flexible mean for erythrocytes adaptions?
Well developed cytoskeleton allows erythrocytes to change shape so can twist and turn as travel through very narrow capillaries
152
What does losing most of their organelles mean for erythrocytes adaptions?
No nucleus, mitochondria, rough endoplasmic reticulum and very little cytoplasm
Provides more space for haemoglobin
153
When is haemoglobin synthesised?
Immature erythrocytes while they still have nucleus, ribosomes and rough endoplasmic reticulum
154
What does being concave mean for erythrocytes adaptions?
Increase surface area to volume ratio
155
How are spermatozoa specialised?
Many mitchrondria
small but long and thin
When reaches ovum releases enzymes from acrosome.
Head of sperm contains haploid male gamete nucleus and very little cytoplasm
156
What does many mitochondria mean for spermatozoa adaptations?
Carry out aerobic respiration
| ATP provides energy for unduplipodium to move and propel cell towards the ovum
157
What does small but long and thin mean for spermatozoa adaptations?
Can move easily
158
What does enzymes mean for spermatozoa adaptations?
Enzyme digests outer protective covering of ovum allowing sperm head to enter the ovum
159
Where is epithelial found?
On outside of body and on inside making up walls of alveoli and capillaries and lining of intestine
160
Shape of epithelial cells
Flattened in shape
161
Do many cells in epithelium have cilia?
Yes
162
How are palisade cells adapted?
Long and cylindrical
Large vacuole
Many chloroplasts
Contain cytoskeleton threads and motor proteins
163
What does long and cylindrical mean for palisade cells?
They pack together quite closely with little space between them for air to circulate carbon dioxide in these air spaces diffuses into the cells
164
What does large vacuole mean for palisade cells?
Chloroplasts are positioned near to the periphery of the cell reducing the diffusion distance for carbon dioxide
165
What does contain cytoskeleton threads and motor proteins mean for palisade cells?
Move chloroplasts nearer to the upper surface if the leaf when sunlight is low but further down when it is high
166
What are guard cells?
A pair of specialised cells
Within lower epidermis
Contain chloroplast can't photosynthesis as don't have enzymes needed
167
What is used to produce ATP in guard cells?
Light energy
168
What lowers water potential in guard cells?
ATP actively transports potassium ions from surrounding epidermal cells
169
What then happens due to the lowered water potential?
Water enters from neighbouring epidermal cells by osmosis
170
Once water has entered ?
Guard cells swell but at tips cellulose wall is more flexible and is more rigid. Where thicker. Tips bulge and half between stoma enlarges
171
Once the guard cells swell?
Stomata open air can enter spaces within layer of cells between palisade cells
172
Once stomata open?
Gaseous exchanges can occur and carbon dioxide will diffuse in palisade cells used for photosynthesis maintaining steep concentration gradient.
173
What happens to the oxygen produced during photosynthesis?
Can diffuse out of palisade cells into air species and out through open stomata
174
What are root hair cells?
Epidermal son the outer layer of young plant root.
175
What adaptations does a root hair cell have?
Hair-like projections
Mineral ions active transported into root hair cell
Special carrier proteins
Cell produces ATP
176
What does hair-like projections mean for adaptations of root hair cells?
Greatly increase surface area for absorption of water and mineral ions such as nitrates from the soil into which it projects
177
What does mineral ions are actively transported into root hair cell mean for adaptations of root hair cells?
Lowers water potential within them causing water to follow by osmosis down the water-potential gradient
178
What does special carrier proteins mean for adaptations of root hair cells?
It's inside the plasma membrane in order to actively transport the mineral ions in
179
What does produce ATP mean for adaptations of root hair cells?
Needed for active transport
180
Define tissue
A group of similar cells working together to perform a certain function
181
What are the four main tissue types?
Epithelial/lining tissue
Connective tissue
Muscle tissue
Nervous tissue
182
What does connective tissue do?
Holds structures together and provides support e.g. Blood, bone, cartilage
183
Muscle tissue is made of?
Cells specialised to contract and cause movements
184
Nervous tissue made of?
Cell specialised to conduct electrical impulses
185
What's epithelial tissue?
Covers and lines free surfaces in the body such as the skin, cavities of the digestive system, blood vessels, heart chambers and walks of organs
186
Characteristics of epithelial tissue are:
```
Made up almost entirely of cell
Cells very close together
No blood vessels
smooth surfaces or have projections cilia/microvilli
Short cell cycles
Specialised to carry out its function
```
187
What does the cells being close together mean?
Form continuous sheet adjacent cells bound together by lateral contacts such as tight junctions and dsmosomes
188
What does no blood vessels mean?
Cells receive nutrients by diffusion from tissue fluid in underlying connective tissue.
189
What do short cell cycles mean?
Only lasts a day so can repair quickly
190
How are epithelial specialised for their function?
Ciliated have cilia that beat particles away
| Squamous epithelial are very thin to allow efficient diffusion of gases
191
Sperm cells special adaptations?
Flagellum so can swim to egg
Lots of mitchrondria to provide ATP to swim
Acrosome contains digestive enzymes to enable sperm to penetrate surface of egg
192
What a tissue?
Group of tissue specialised to work together to carry out a particular function. Tissue contains more then one cell type
193
Name four types of tissue?
Squamous epithelium
Ciliated epithelum
Muscle tissue
Cartilage
194
Squamous epithelium?
single layer of flat cells lining a surface. Found in many places including alveoli in lungs.
195
Ciliated epithelum?
Layer of cells covered by cilia
Found in surface where things need to be moved
(Trachea cilia waft mucus along)
196
Muscle tissue made of?
Made up of bundled of elongated cells (muscle fibres)
197
Types of muscle tissue and are they all the same?
Smooth
Cardiac
Skeletal
Slightly different in structure
198
Cartilage is?
Type of connective tissue in joints
Shaped and supports ears, nose and windpipe
Formed when cells (chrondroblasts) secrete extra cellular matrix become trapped inside
199
Xylem tissue?
Transports water around plant
Supports plant
Contains hollow xylem vessel cells
Living parenchyma cells
200
Phloem tissue?
Transports sugars around plant
Arranged in tubes made of sieve and companion cells and some ordinary plant cells
Sieve cells has sieve plates so sap can move easily though
201
Organ?
Group of tissue work together to perform particular function.
202
Name examples of organs?
Lungs contain squamous epithelial tissue, ciliated epithelial tissue, elastic connective tissue and vascular tissue
Leaves contain palisade tissue photosynthesis, epidermal tissue, xylem and pholem in veins
203
What do organs work together to form?
Organ systems each with particular function
204
Name two examples of organ system?
Respiratory system
| Circularity system
205
Respiratory system?
Function breathing
| Made of lungs, nose, mouth, diaphragm
206
Circularity system?
Blood supply
| Heart, artery, veins and capillaries
