2.1.6 Cell Divison, Cell Diversity and Cellular Organisation Flashcards
1
Q
What are the phrases of the cell cycle?
A
Growth 1 Synthesis Growth 2 Mitosis Cytokinesis
2
Q
What are the 2 phases of the cell cycle? CC
A
- Interphase
2. Miotic
3
Q
What happens during Growth 1? CC
A
- Organelles replicate
- Cell size increases
- Protein synthesis
- Respiration
- G1 Checkpoint
4
Q
What happens during Growth 2? CC
A
- Duplicated DNA checked for errors
- Cell size increases
- Energy store increases
- G2 checkpoint: DNA replication error, everything in G1
5
Q
What happens during Synthesis? CC
A
- Splitting cytoplasm into 2 daughter cells which will start the cell cycle
6
Q
What happens if a checkpoint detects an error in the cell cycle?
A
Enters G0/ resting phase
7
Q
What are reasons for entering G0 phase? (3) CC
A
- Differentiation- specialised cells don’t replicate
- DNA Damage- no longer divides
- Senescent cells- max. no. of division
8
Q
What regulates the cell cycle?
A
Checkpoints
9
Q
Why do cells need mitosis?
A
- Growth
- Repair
- Sexual reproduction
10
Q
Abbreviation for the Mitosis phases?
A
PMAT
Prophase, metaphase, anaphase and telophase
11
Q
What happens during Interphase? Way to remember?
A
- DNA = chromatin
- DNA replicates
I = Invisible chromosomes
12
Q
What happens during Prophase? Way to remember? (Mitosis)
A
- Chromatin condenses = Chromosomes visible
- Nucleolus disappears
- Centrioles move to poles
- Nuclear envelope breaks down
P = centrioles to Poles
13
Q
What happens during Metaphase? Way to remember? (Mitosis)
A
- Spindle fibres attach to centrosomes
- Chromosomes line up on equator
M = middle (equator)
14
Q
What happens during Anaphase? Way to remember? (Mitosis)
A
- Spindle fibres shorten
- Chromosomes divided into Chromatids
- Chromatids are separated to either pole
A = away to poles
15
Q
What happens during Telophase? Way to remember? (Mitosis)
A
- Nuclear envelopes form around daughter chromosomes/ chromatids
- Chromosomes invisible
- Cytokinesis
T = Two indentical daughter chromosomes/ chromatids
16
Q
What is Cytokinesis? Differences in plants/ animals? Way to remember? (Mitosis)
A
- Cells separate producing two identical daughter cells
- Animals: cleavage furrow
- Plants: cell wall production
C = Cleavage
17
Q
What is Chromatin?
A
DNA wrapped around histone proteins
18
Q
What are centrioles? Function?
A
- Part of centrosome in cell: 2 centrioles per centrosome
- Produce spindle fibres
19
Q
What are spindle fibres? Function?
A
- Microtubules produced from centrioles
- Attach to centrosomes + shorten to poles
20
Q
What is a Centromere?
A
Where chromatids are joined in a chromosome
21
Q
What is a Chromatid?
A
Single- stranded chromosome
22
Q
What are the 3 differences in Mitosis between animals and plants?
A
- (A) Centrioles (P) none
- (A) cells rounded before (P) no shape change
- (A) spindle fibres go before split (P) some spindle fibres present
23
Q
Abbreviation for the Meiosis phases?
A
PMAT & PMAT2
24
Q
How many chromosomes do gametes have?
A
23
25
What is meiosis?
Nuclear division, haploid cells produced
26
What happens in Prophase I? Way to remember? (Meiosis)
- Nuclear envelope & nucleolus disappears
- Spindle fibres formed
- Homologous pairs line up
- Bivalents do crossing over
27
What happens in Metaphase I? Way to remember? (Meiosis)
- Homologous chromosomes line up on equator
| Independent assortment
28
What happens in Anaphase I? Way to remember? (Meiosis)
- Homologous chromosomes pairs are separated
| Random segregation
29
What happens in Telophase I? Way to remember? (Meiosis)
- Chromosomes at either pole
- Cytokinesis- cleavage
- 2 haploid cells formed
30
What happens in Prophase II? Way to remember? (Meiosis)
- Chromosomes condense
- Nuclear envelope & nucleolus disappears
- Spindle fibres formed
31
What happens in Metaphase II? Way to remember? (Meiosis)
- Chromosomes line up on equator
| Independent assortment
32
What happens in Anaphase II? Way to remember? (Meiosis)
- Random segregation of Chromatids
33
What happens in Telophase II? Way to remember? (Meiosis)
- Chromatids at either poles
- Cytokinesis
- 4 haploid daughter cells formed
34
What is a homologous chromosome?
A chromosome with 2 chromatids; same size and DNA in same order
35
What is a bivalent?
Two chromosomes with 4 chromatids; two homologous chromosomes crossing over and temporarily joined
36
What is crossing over?
Homologous chromosomes exchanging codes for specific genes
37
What is independent assortment?
Chromosomes align on equator in random orientation
38
What is random segregation?
Chromosomes align on equator in random orientation and are separated
39
What is a haploid cell?
Half number of chromosomes in nucleus
40
Why are cells haploid after Meiosis I?
46 chromatids -> 92 chromatids -> 46 chromatids
| .. technically 46 chromosomes -> 92 chromosomes -> 46 chromosomes bc centromeres are counted
41
How does crossing over cause genetic variation?
New combination of alleles
42
How does independent assortment cause genetic variation?
Different combination of chromosomes in haploid cell
43
How does random segregation cause genetic variation?
Different combination of chromatids in haploid cell/ gamete
44
What is a tissue?
Group of differentiated cells that work together; specific function
45
What are the examples of tissue you need to know? (6)
1. Squamous epithelium
2. Ciliated epithelium
3. Cartilage
4. Skeletal muscle
5. Xylem
6. Phloem
46
What is an organ?
Collection of several tissues that work together for specific function(s)
47
What is an organ system?
Group of organs that work together to perform a function
48
Smallest to largest organisation of cells?
Specialised -> tissue -> organ -> organ system
49
What is a specialised cell?
Differentiated cell from stem cell; structure -> specific function
50
What are the examples of specialised cells you need to know? (6)
1. Erythrocytes
2. Neutrophils
3. Sperm cells
4. Palisade cells
5. Root hair cells
6. Guard cells
51
What is a stem cell?
Undifferentiated cells; haven;t specialised for specific function
52
Why are stem cells important in an organism?
- Growth
- Development
- Tissue repair
53
Stem cells are a source of what and why?
- Undifferentiated cells
| - Can do cellular division many times
54
Where do blood cells in animals come from?
Stem cells; bone marrow
55
Where do xylem vessels and phloem sieve tubes come from in plants?
Stem cells; meristem
56
Examples of stem cells being used as medicine?
- Repair damaged tissue
| - Treat neurological conditions
57
Why is using stem cells in medicine sometimes seen to be unethical?
Embryonic cells; potential life
58
What is totipotent? Way to remember?
- Stem cells that can specialise as any specialised cell
| - Potential to be whole organism
59
What is Pluripotent?
- Stem cells that can specialise as any specialised cell
| - No potential to be whole organism
60
What is Multipotent?
Stem cells that can only specialise within a LIMITED range of specialised cell
61
How are guard cells specialised?
Can increase/ decrease size determining if stoma is open
62
How are root hair cells specialised?
- Long, narrow -> large SA
| - Large vacuole, high conc. of solute -> increase osmosis
63
How are palisade cells specialised?
- Lots of chloroplasts- more light = photosynthesis
- Thin walls -> more CO2 diffusion
- Large vacuole -> turgor pressure
64
How are sperm cells specialised?
- Flagella -> movement
- Lots mitochondria -> energy for movement
- Acrosome -> digest exterior of egg, penetration
65
How are neutrophils specialised?
- Multi-lobed -> fit through capillary wall gaps
| - Many lysosomes -> hydrolytic enzymes (destroy pathogens)
66
How are erythrocytes specialised?
- Flattened bioconcave shape with no organelles -> increase SA = more oxygen carried
67
2 Animal and plant examples of organ system?
A: digestive; respiratory
P: shoot; root
