Biology 3202 Quiz 1 Flashcards
(38 cards)
This meiotic process is key in the recombination of genes necessary for genetic variation
Crossing Over
When does duplication of chromosomes occur in meiosis
S phase
Each sperm cell contains:
22 autosomes and 1 X chromosome
Meiosis occurs in:
The ovaries and testes
Meiosis results in:
Eggs, Gametes, and sperm.
All human somatic cells are:
Diploid (2n) with 46 chromosomes
What is the purpose of Meiosis?
The purpose of meiosis is to produce gametes, or sex cells. During meiosis, four daughter cells are produced, each of which are haploid (containing half as many chromosomes as the parent cell).
What are the differences in Spermatogenesis and oogenesis?
Spermatogenesis:
-Occurs in the testes/male
-Occurs from puberty-end of life
-Equal division of the cytoplasm
-Ends at meiosis 2 with 4 haploid spermatids
Oogenesis:
-Occurs in the ovaries/female
-Starts before birth, stops, then starts again until menopause
-Unequal division of the cytoplasm which results in polar bodies (they die)
-1 visible egg (haploid) while polar bodies die
What are the differences between mitosis and meiosis?
Mitosis:
-Results in 2 identical daughter cells (2n)
-1 Division (PMAT)
-Line up at single file during metaphase + chromatids separate in anaphase
-crossing over in prophase 1
Meiosis:
-Results in 4 distinct daughter cells (n)
-2 PMAT divisions
cell membrane
A double layer that supports and protects the cell. Allows materials in and out.
Lysosome
Contains digestive enzymes that destroy damaged organelles and invaders.
cytoplasm
Jelly-like fluid that surrounds and protects the organelles.
Nucleus
The control center of the cell. Contains the DNA
Nuclear Membrane
Surrounds the nucleus.
nucleolus
A round structure in the nucleus that makes ribosomes.
vacuole
stores food and water
mitochondria
The “Powerhouse”. Breaks down food to produce energy in the form of ATP.
Rough E.R
Builds and transports substances through the cell. Has ribosomes on it.
Smooth E.R
Builds and transports substances through the cell. Doesn’t have ribosomes on it.
Ribosome
Helps make proteins for the cell.
cell wall
Gives shape and protection to plant cells.
chloroplast
Changes sunlight into sugar for plant cells. Contains a green pigment called chlorophyll.
Which Phase?
* the chromatin condenses into tightly packed chromosomes.
* The nuclear membrane breaks down, releasing the chromosomes into the cytoplasm.
* The nucleolus disappears.
* One pair of centrioles move apart to opposite poles of the cell.
* As the centrioles move apart, a network of fibres called the spindle fibres forms
between them. Each spindle fibre is made of microtubules
Prophase
Which Phase?
* The spindle fibres guide the chromosomes to the equator, or centre line, of the
* cell.
* The spindle fibres from opposite poles attach to the centromere of each chromosome.
Metaphase