B13 Reproduction Flashcards
paper 2
What is sexual reproduction?
joining (fusion) of male and female gametes
What type of cell division is involved in sexual reproduction?
meiosis
What type of cell division is involved in asexual reproduction?
mitosis
What is meiosis?
cell division that produces four non-identical daughter cells (gametes), each with a single set of chromosomes.
What are the male and female sex chromosomes in humans?
XX - female
XY - male
what are the male and female gametes in flowering plants.
pollen - male gamete
ovule - female gamete
What is the genetic material in cells called?
DNA
What is the structure of DNA?
two complementary polymer stands forming a double helix
What is a gene?
small section of DNA that codes for a particular amino acid sequence, to make a specific protein.
What are alleles?
different forms of the same gene
What is a recessive allele?
allele that needs to be present twice to be expressed
What is a dominant allele?
allele that is always expressed, even if only one copy is present.
What is a genome?
the entire genetic material of an organism
Define the term homozygous.
two of the same alleles present in an organism
Define the term heterozygous.
two different alleles present in an organism
What type of allele causes polydactyly?
dominant allele
What type of allele causes cystic fibrosis?
recessive allele
How many chromosomes do normal human body cells have?
23 pairs (46)
Why is studying the human genome important?
- search for genes linked to certain diseases
- understanding and treatment of inherited disorders
- tracing past human migration
