Sexual reproduction Flashcards
Where is the DNA
In a cell’s nucleus within a structure called chromosomes
How many chromosomes are in a human body
46 (23 pairs)
What is in a pair of chromosomes
One chromosome is inherited from the organism’s mother (maternal chromosome) an another is inherited from the organism’s father (paternal chromosome).
What is the 23rd pair of chromosomes
This is known as a sex chromosome. Females have 2 X chromosomes whereas Males have an X and Y chromosome.
What is meiosis
A special type of cell division of in sexually reproducing organisms that produces the gametes such as sperm or egg cells. It involves two rounds of division that ultimately result in four cells with one copy of each chromosome.
What are gametes
They are an organism’s reproductive cells. They are also known as sex cells
Fertilisation in humans
There are 23 chromosomes within a gamete. When egg and sperm cells combine in fertilisation, they merge the two sets of chromosomes, ending up with 46 in total. The resultant cell is called a zygote; it is a diploid as it has 2 copies of every chromosome. The zygote will grow by mitosis and mature into an embryo.
What is mitosis
Mitosis is a type of cell divisionused for growth andrepair. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintained.
