Sexual Reproduction Flashcards
Sexual Reproduction
Involves the mixing of genetic materials from each of the two parents in the form of gametes.
What is the form of gametes in animals?
Egg and Sperm Cells
Gamete
Reproductive cells that has a single set of unpaired chromosomes and can join with another cell to reproduce
In humans and most domestic animals, what do females produce?
Egg
In humans and most domestic animals, what do males produce?
Sperm
Hermaphrodites
some species that have both egg and sperm producing organs
Example of a ‘hermaphrodite’ species:
Garden Snail
Simultaneous (synchronous) hermaphrodism
Species that have both egg and sperm producing organs at all times
Sequential Hermaphrodites
Species that can change between sexes (some fishes)
Diploid
Carrying two sets of chromosomes
Denotation of ‘diploid’:
2n
How many chromosomes do humans have?
46
How many chromosome pairs do humans have?
2n=46, therefore they have 23 pairs
What do chromosomes carry?
Genetic Information
Which parent contributes genetic material to the new offspring?
Each parent contributes the same amount of genetic material to the new offspring
How does it make sure that the offspring has only 46 chromosomes?
The parents produce gametes that are haploid.
Haploid
1 set of chromosomes, not 2. They only contain 23 chromosomes.
Detonation of haploids:
n
How many diploid cells in humans?
2n=46 (diploid cells, somatic cells)
How many haploid cells in humans?
N=23 (haploid cells, gametes)
Meiosis
Process used to produce gametes. This involves the production of the new cells with half the amount of chromosomes
Why are offsprings not identical to their parents in Meiosis?
There is a ‘shuffle’ of genetic information therefore the offsprings aren’t identical to their parents.
What are the 3 key events that occur during meiosis?
- Halving of chromosomes, results cells have one of each chromosome
- Ends with 4 haploid cells
- Mixing of genetic combinations (crossing over)
What are the stages in Meiosis?
- Interphase
- Meiosis (1)
a. Prophase (1)
b. Metaphase (1)
c. Anaphase (1)
d. Telophase (1) - Cytokinesis (1)
- Meiosis (2)
a. Prophase (2)
b. Metaphase (2)
c. Anaphase (2)
d. Telophase (2) - Cytokinesis (2)
What produces variation in offsprings?
Recombination
Nondisjunction
Chromosomes do not separate
What is the result of a nondisjunction?
There will be one gamete containing 2 sets of chromosomes, whilst one gamete will be lacking
Advantages of Meiosis
- Genetic diversity
- Increased survival chances
Disadvantages of Meiosis
- Energy and commitment required to find a mate
- Methods of reproduction, might take more than one attempt
How many eggs are produced in Meiosis?
1 egg and 3 polar bodies
How many sperm cells are produced in Meiosis?
4 sperm cells for each cycle
The process of crossing over occurs in which stage?
Prophase (1)
Are daughter cells in Mitosis, diploid or haploid?
Diploid
Are daughter cells in Meiosis, diploid or haploid?
Haploid
How many daughter cells are produced after Mitosis?
2 daughter cells
How many daughter cells are produced after Meiosis?
4 daughter cells
