Cell Reproduction Flashcards
True or false: somatic and reproductive cells reproduce differently
true
What is generated during somatic cell division?
two genetically identical cells
How many chromosomes does a somatic cell have?
46
What is the division of the nucleus in somatic cell division called?
mitosis
What is generated during reproductive cell division?
produces gametes (sperm and egg), 4 non genetically identical cells
How many chromosomes do gametes have?
23
What is the division of the nucleus in reproductive cell division called?
meiosis
What is the division of the cytoplasm called?
cytokinesis
What are somatic cells that contain 23 pairs of chromosomes called?
diploid (2n) cells
What are homologous chromosomes?
the two chromosomes of the pair, they look very similar
What is different about sex chromosomes?
designated X (large), Y (small)
What is a female sex chromosome?
XX
What is a male sex chromosome?
XY
What does a somatic cell go through in its life cycle?
interphase and mitotic (m) phase
What is the cell cycle?
conventionally the interphase and mitotic phase of a somatic cell can be fit into a 24 hr cycle
What is G0 phase of interphase?
cells stay in G1 phase for a long time and may not reproduce, the exit cycle and stay in G0 phase
Give examples of body cells arrested in the G0 phase
skeletal muscle cell, neurons
What are chromatids?
the chromosomes during the mitotic prophase become visible as a pair of identical strands
What is a centromere?
it holds the chromatid pair together
When do the nuclear envelope and the nucleolus disappear during mitosis?
later in prophase
During metaphase what is aligns the centromeres of the chromatid pairs at the centre of the cell?
mitotic spindle
What is the visible alignment of the chromatid pairs in the middle of the cell during metaphase called?
metaphase plate
What is the main thing that happens in anaphase?
The chromosomes move to the opposite poles of the cell dragged from the centromeres by the spindle, so they appear V-shaped
When does mitotic telophase begin?
Begins after the chromosomal movement stops
When does mitotic telophase stop?
Ends when cytokinesis is completed
What happens during cytokinesis?
Begins in late anaphase forming the cleavage furrow
What is a cleavage furrow?
A contractile ring pulls the plasma membrane inward
What begins once cytokinesis is completed?
When cytokinesis is completed, interphase begins
What is the nuclear division of reproductive cells called?
The nuclear division is called meiosis, where the number of chromosomes is reduced by half
How many chromosomes do gametes contain?
Gametes contain a single set of 23 chromosomes
What types of cells are gametes?
Gametes are haploid (n) cells
When does Meiosis I begin?
Begins after the chromosomal replication is completed
How does prophase I differ from mitotic prophase?
The Prophase I (is an extended phase)
What is a tetrad?
Two sisters chromatids of each homologous chromosome pair off and form a tetrad (four chromatids)
what does crossing over result in?
Parts of the chromatids within the tetrads may be exchanged with one another in the process called crossing-over.
• This results in a genetic recombination
When do tetrads line up along the metaphase plate?
Metaphase I
What happens during anaphase I?
The members of each homologues pair separate and are pulled to the opposite poles of the cell
The paired chromatids do not split, they remain together in this phase
Each resulting cell of Meiosis I has _______(_) number of chromosomes
Each resulting cell of Meiosis I has haploid (n) number of chromosomes
True or false: after meiosis I each cell contains only one member of each pair of the homologous chromosomes present in the starting cell
True
True or false: meiosis II is similar to mitosis
True
What is the net result of meiosis II?
The net result of Meiosis II will be four haploid cells genetically different from the starting diploid cell
What are the three possible destinies of cells?
- Remain alive and functional without dividing
- Grow and divide
- Die
What keeps the balance between cell proliferation and cell death?
Homeostasis keeps a balance between cell proliferation and cell death
What within a cell can activate a protein for functioning?
The enzymes cyclin-dependent protein kinases (Cdk’s) within the cell can activate a protein for functioning
What within a cell can deactivate a protein?
Other enzymes can deactivate a protein
What is the activation of Cdk’s at the appropriate time crucial for?
- DNA replication
- Mitosis
- Cytokinesis
What switches Cdk’s on and off?
Cellular proteins call cyclins switch Cdk’s on and off
What is apoptosis?
normal type of cell death
What is necrosis?
pathological cell death
What is gerontology?
Gerontology is the scientific study of the process and problems associated with aging
What is geriatrics?
Geriatrics is the branch of medicine that deals with the medical problems and care of elderly persons.
What is cessation of mitosis?
Cessation of mitosis is a normal genetically programmed event
Normal cells divide only for certain number of times and then stop
What are telomeres?
Telomeres are DNA sequences only found at the tips of the chromosomes
• Protect the chromosomes from erosion and from sticking to one another
What happens to telomeres after each cycle?
Telomeres shorten after each cell cycle
With age why do tissues lose elasticity and stiffen?
With age, the immune system may start attacking the body’s cells
