4.6.1 Reproduction (will come up) P2 Flashcards
What is sexual reproduction
Type of reproduction
Involves the production of gametes by meiosis
A gamete from each parent fuses to form a zygote
Genetic information from each gamete is mixed so the resulting zygote is unique
What are gametes
Sex cells (sperm + egg, pollen + egg) Haploid cells (half the number of chromosomes)
What is meiosis
Form of cell division involved in the formation of gametes in reproductive organs
Chromosome number is halved
Involves 2 divisions
What must occur prior to meiosis
Interphase - copies of genetic information are made during this process
What happens during the first stage of meiosis
Chromosome pairs line up along the cell equator
The pair of chromosomes are separated and move to opposite poles of the cell
Chromosome number is halved
What happens during the second stage of meiosis
Chromosomes line up along the centre of cell
The chromatids are separated and move to opposite poles of the cell
Four unique haploid gametes are produced
Why is meiosis important for sexual reproduction
It increases genetic variation
It ensures that the zygote formed at fertilisation is diploid
Describe fertilisation and its resulting outcome
Gametes join together to restore the normal number of chromosomes and the new cell then divides by mitosis
As the embryo develops, cells differentiate
What is asexual reproduction
Involved mitosis only
Produces genetically identical daughter cells
Asexual reproduction involves only one parent and no fusion of gametes.
What is DNA
A double-stranded polymer of nucleotides, wound to form a double helix
Define genome
The entire genetic material of an organism
Why is understanding the human genome important
Important for the development of medicine in the future
Searching for genes linked to different types of disease
Understanding and treating inherited disorders
Tracing human migration patterns from the past
What is a chromosome
A long, coiled molecule of DNA that carries genetic information in the form of genes
How many chromosomes do human body cells have
46 (23 pairs)
How many chromosomes do human gametes have
23 chromosomes