Biology 3202 Quiz 1 Flashcards
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
Which phase?
Each centromere splits apart and the sister chromatids separate from one another.
* The spindle fibres that link the centromeres to the poles of the cell shorten. As these
fibres shorten, sister chromatids are pulled to opposite poles.
* At the end of anaphase, one complete diploid set of chromosomes has been gathered at
each pole of the elongated cell.
Anaphase
- The chromatids begin to unwind into the longer and less visible strands of chromatin.
- The spindle fibres break down.
- A nuclear membrane forms around each new set of chromosomes
- A nucleolus forms within each new nucleus.
Telophase
A is an identical genetic copy of it’s parent
Clone
in Only one parent is required to produce offspring
Asexual Reproduction
Some simple organisms, such as hydras, sponges, and yeast, are able to reproduce asexually by by allowing offspring to begin as a growth on the parent
Budding
Certain species of sea stars, corals, and mosses can reproduce asexually by where pieces of the parents body break off and grow into new organisms
Fragmentation
occurs when special cells in the stems and roots divide repeatedly to form structures that eventually develop into a plant identical to the parent
Vegetative reproduction
Reproductive Cells that develop into new individuals by repeated mitosis when the conditions are correct
Spores
Single parent cell splits into two equal parts that have the same copies of genetic material
Binary Fission
What are the advantages and disadvantages of asexual reproduction?
Advantages Disadvantage
- 1 Parent Cells -Lack of genetic
diversity
-Reproduction is faster - a catastrophe could
happen that could wipe
out an entire species
What is dividing during cytokinesis
cytoplasm
What is the non-condensed form of genetic material, in which form genetic information is usually found?
chromatin
What is the purpose of the acrosome on the sperm cell?
To penetrate the egg
If oogonium with 50 chromosomes undergoes oogenesis, how many chromosomes are present in daughter cells
25
