2.3 Eukaryotic cell cycle Flashcards
1
Q
What is cell division in prokaryotic cells called?
A
- Binary fission.
2
Q
What is cell division in eukaryotic cells called?
A
- Cell cycle.
3
Q
What are the 3 steps in the cell cycle?
A
- Interphase.
- Mitosis.
- Cytokinesis.
4
Q
What is the cell cycle used for in unicellular organisms?
A
- Asexual reproduction.
5
Q
What is the cell cycle used for in multicellular organisms?
A
- Growth + repair.
6
Q
What is asexual reproduction?
A
- Formation of new organisms that does not involve fusion of gametes.
7
Q
What are chromosomes made of?
A
- Sequence of nucleotide bases in DNA.
8
Q
What are the 3 features of chromosomes?
A
- Shape of each chromosome is characteristic.
- Chromosomes occur in homologous pairs.
- For each species, number of chromosomes is fixed.
9
Q
What is a centromere?
A
- Narrow region occupying specific position on each chromosome.
- Only site on each chromosome that spindles can attach to during mitosis.
- Following DNA replication, centromere holds together 2 chromatids.
10
Q
What is a stomatic cell?
A
- Any cell in body of multicellular organism other than germ cell or undifferentiated stem cell.
11
Q
What are homologous chromosomes?
A
- Pair of c’somes in a diploid cell that have same shape + size.
- Carry same genes in same order although not necessarily same alleles of each gene.
12
Q
What does diploid mean?
A
- Contains 2 copies of each c’some.
- In sexually reproducing organisms, one copy from each parent.
13
Q
How many pairs of c’somes and number of c’somes do humans have?
A
- 23 pairs.
- 46 c’somes.
14
Q
What is a karyotype?
A
- Number + shape of c’somes.
15
Q
What is a locus (plural loci)?
A
- Position that a particular gene occupies on a specific c’some.
16
Q
What are alleles?
A
- 1 of 2 or more diff forms of same gene.
- Diff alleles of same gene have slightly diff nucleotide sequences.
17
Q
What does homozygous mean?
A
- Diploid cells have 2 copies of each gene.
- If 2 copies are same allele of gene, cell is homozygous.
18
Q
What does heterozygous mean?
A
- Diploid cell, 2 copies of a gene are diff alleles, cell is heterozygous for this gene.
19
Q
What are chromatids?
A
- Following DNA replication, cell has 2 copies of each chromosome.
- When these become visible during cell division, held together by centromeres, briefly called chromatids.
20
Q
What is a karyogram?
A
- Images of c’somes cut from copy of photomicrograph are arranged + pasted.
21
Q
What are sex c’somes?
A
- c’some that carries genes which determine sex of an organism.
- In mammals, Y c’somes determines maleness.
22
Q
What is an autosome?
A
- Any c’some other than a sex c’some.
23
Q
What is interphase?
A
- Time between divisions.
24
Q
What is mitosis?
A
- Separation of chromatids of each c’some to form 2 new nuclei.
25
What is cytokinesis?
- Division of cytoplasm.
26
What are the 3 parts of interphase?
- G1 - 1st growth phase.
- S - Synthesis of DNA.
- G2 - 2nd growth phase.
27
What happens during the 1st growth phase during interphase?
- Cytoplasm active.
- New organelles formed.
- Intense biochemical activity of growing cell.
28
What happens during the synthesis of DNA during interphase?
- Chromosomes replicated --> chromatids.
29
What happens during the 2nd growth phase during interphase?
- More growth of cell.
- Preparation for mitosis.
30
What is the longest part of the cell cycle?
- Interphase.
31
What are the stages involved in mitosis?
- Prophase.
- Metaphase.
- Anaphase.
- Telophase.
32
What is mitosis?
- Nuclear division.
33
What happens during prophase?
- **Super-coiling** - c'some shorten + thicken (visible as 2 sister chromatids joined at centromere).
- Centrioles split + move to opp ends of cell --> spindle extends across cell.
- Nuclear envelope disintegrates - c'somes freed into cytoplasm.
34
What happens during metaphase?
- Nuclear envelope completely gone.
- Spindle fibres attach to centromeres of c'somes.
- Spindle fibres pull c'somes to equator.
35
What happens during anaphase?
- C'somes break apart at centromere.
- Splits into 2 v-shaped sister chromatids.
36
What happens during telophase?
- Chromatids reach opp ends of cell.
- Chromatids uncoil + become c'somes again.
- Nuclear envelope reforms around c'somes.
- Cell prepares to slipt cytoplasm + contents (**cleavage furrow** forms).
37
What happens in cytokenesis?
- Cell splits into 2 daughter cells.
- Daughter cells identical to each other **and** parent cell.
38
What are daughter cells called?
- Clones.
39
What is a clone?
- 2 or more cells (or organisms) genetically identical.
40
How are clones made in eukaryotic organisms?
- Mitosis.
41
Why does mitosis produce clone daughter cells?
- Because DNA directly replicated during interphase.
- Cytoplasm divided down mid-point during cytokinesis.
42
Where does mitosis commonly occur in animals?
- Epithelial tissues - e.g. skin + lining of intestine.
43
Where does mitosis commonly occur in flowering plants?
- Found in **meristems** - actively growing tips of shoot + roots.
- **Cambium** - vascular bundles.
44
What is Meristem?
- Group of plant tissues able to divide by mitosis.
45
What are primary meristems?
- Found at tips of growing shoots and roots.
46
What are secondary meristems?
- Develop in woody plants, leading to increase in diameter of roots + shoots.
