Inheritance

• How many chromosome pairs does a human call contain

  23
• I humans what are the gametes

  Sperm and egg cells
• in gametes are the chromosomes paired or single

  Single
• does meiosis produce identical cells ?

  No
• What is sexual reproduction

  The fusion of male and female gametes
• in sexual reproduction There is a mixing of genetic information
• Asexual reproduction does not involve gametes
• Because asexual reproduction does not involve gametes meiosis does not take place
• Asexual reproduction only involves mitosis
• In asexual reproduction there are no sexes so the offspring will be genetically identical to their parent
• Variation can lead to new traits that may give an advantage over other organisms
• in gametes the chromosomes are not paired, they are single
• Where does meiosis take place

  Reproductive organs
• in the first stage of meiosis the chromosomes are copied
• in the second stage of meiosis the cell then divided in two
• In the third stage of meiosis the cells divide one more time forming the gametes
• Meiosis produces how many gametes from one original cell ?

  4
• The process of meiosis ensures variation as it involves crossing over which shuffles genes around on the chromatids
• the number of chromosomes is halved during meiosis so that when fertilisation occurs there will be the correct amount of genetic material to form an embryo
• in sexual reproduction, two gametes join together to get the normal amount of chromosomes
• In meiosis the number of chromosomes is halved but in fertilisation the full number of chromosomes is restored
• After fertilisation, the new cell divides by mitosis producing a clump of identical cells
• What is each strand in dna called

  A polymer
• In DNA the two strands wrap around each other to form a double helix
• A gene is a small section of DNA on a chromosme
• Each gene encodes for a specific sequence of amino acids to make a specific protein
• What is a genome

  The entire genetic material of an organism
• Understanding the human genome will help us to search for genes that are linked to a disease
• Understanding the human genome will help us understand and treat inherited disorders like cysic fibrosis
• We can use the human genome to trace human migration patterns from the past
• One chromosome in the pair come from your father and one comes from your mother
• Genes are sections of DNA on a chromosome
• Alleles are versions of a gene
• The genotype of a person tells us the alleles are present
• if a person has two copies of the same allele, scientists say they are homozygous
• The phenotype of a person tells us the characteristics caused by the persons alleles
• Two different alleles are called heterozygous
• Cystic fibrosis is a disorder of cell membranes
• Cystic fibrosis is recessive
• If a person has one allele for cystic fibrosis they are called a carrier