SB3b Meiosis Flashcards
What happens when the nuclei of two gametes (sex cells) fuse during fertilisation?
they form a zygote.
The zygote divides by mitosis and forms what?
an embryo.
Why does the zygote divide by mitosis?
So that all the cells in the embryo (stem cells) are genetically identical.
What are the names of human gametes?
sperm and egg.
How many chromosomes are in human sperm cells?
23.
How many chromosomes are in human liver cells?
46.
Are body cells diploid or haploid?
they are diploid - contain two copies of each chromosome (2n).
Are gametes diploid or haploid?
they are haploid - contain one set of chromosomes (n).
How many chromosomes do human diploid cells contain?
46.
How many chromosomes do human gametes contain?
23.
What is a genome?
the DNA of an organism.
In how many chromosomes is the human genome found?
46.
What is a section of DNA called?
a gene and codes to make proteins.
How many genes do humans have?
about 20 000.
Gamete production process? (4)
.The gamete-making cell has two sets of chromosomes (they are diploid)
.The chromosomes replicate (and the copies stay stuck together)
.The cell divides into two
.The cell divides into two again. Each of the four final daughter cells has a copy of one chromosome from each pair (they are haploid)
