2. Sexual Reproduction & Meiosis Flashcards
(8 cards)
1
Q
What is a gamete
A
Sex cells (e.g. sperm cells and egg cells) that fuse together during sexual reproduction
2
Q
What happens in sexual reproduction
A
In sexual reproduction 2 gametes (an egg and a sperm) join together at fertilisation to form a zygote. The zygote then divides & develops into a new organism.
3
Q
What is Meiosis
A
- Meiosis is a type of cell division that happens in the reproductive organs to produce gametes.
- Meiosis involves a reduction division. Cells that divide by meiosis have the full no. of chromosomes to start with, but the cells that are formed from meiosis have half the number. Cells w half the normal no. of chromosomes are called haploid cells.
- Cells formed by Meiosis are all genetically different bc each new cell ends up w a different combination of chromosomes.
4
Q
How many chromosomes do human body cells have
A
Human somatic cells (body cells) have 23 pairs of chromosomes. (DO NOT SAY 46)
This is called the diploid number (2n).
5
Q
How many chromosomes do human gametes have
A
Human gametes (sex cells) have 23 chromosomes (no pairs).
This is called the haploid number (n).
6
Q
What does Meiosis consist of
A
Meiosis involves 2 division:
- meiosis 1
- meiosis 2
- Meiosis 1 is the reduction division (it halves the chromosome number).
- Like mitosis, meiosis 1 & 2 are each split into prophase, metaphase, anaphase & telophase stages.
7
Q
What happens during Interphase in Meiosis
A
- The whole of meiosis begins with INTERPHASE.
- During Interphase, the DNA unravels & replicates to produce sister chromatids.
8
Q
A
