Flashcards in B12 Deck (14):
Describe Asexual reproduction
-Done by mitosis
-No fusion of gametes
-No mixing of genetic information
-Leads to genetically identical offspring
-Only 1 parent
Describe sexual reproduction
-Fusion of male and female gametes
-Gametes are formed by meiosis which leads to the formation of non-identical cells (sperm and egg cells in mammals / Pollen and egg cells in plants)
-Mixing of genetical information that leads to variation in the offspring
What is a genome ?
The entire genetic material of an organism
Why is studying the human genome important ?
-Search for genes linked to different types of disease
-Genetic modification to benefit future generations
-understanding treatment of inherited disorders
-tracing human migration patterns from the past
What is DNA ?
-The composition of genetic material in the nucleus
-A polymer made up of two strands forming a double helix
What is a gene ?
-A small section of DNA on a chromosome
-Each gene codes for a particular sequence of amino acids to make a specific protein
What do the following terms mean:
Homozygote: An individual with two identical alleles for a characteristic
Heterozygote: An individual with different alleles for a characteristic
Genotype: Describes the alleles present or genetic makeup of an individual regarding a particular characteristic
Phenotype: The physical appearance of an individual regarding a particular characteristic e.g. black or brown fur in a mouse
What is a dominant and recessive allele ?
Dominant: Only one of these allele must be present to control the characteristic, often represented with a capital letter
Recessive: Both alleles must be present in order to control the characteristic, often represent with a lower case equivalent of the letter
Name 2 genetic diseases and how they are inherited
Polydactyly, development of extra body part e.g. finger:
-Caused by a dominant allele which can be inherited from both parents
Cystic Fibrosis, prevents movement of certain substances in the body leading to a build up of thick mucus:
-inherited via a recessive allele
How can genetical diseases be discovered before a baby is born ?
-Amniocentesis carried out at 15-16 weeks of pregnancy, involves taking fluid around foetus and developing foetus. This fluid contains. Fetal cells which can be used for screening
-Chronic villus sampling done between 10-12 weeks of pregnancy by takin a sample of tissue from the developing placenta which provides fetal cells to screen
What are some disorders that come about by inheritance ?
-caused by a dominant allele and it causes extra fingers or toes
-Caused by a recessive allele, it is a disorder of cell membranes
How does sexual reproduction work in animals and plants ?
-fusion of sperm and egg cells
-Pollen and egg cells fuse
What is meiosis and how does it work ?
Meiosis is the division of cells to form gametes:
-Copies of genetic information are made
-Cells divide twice to form four gametes, each with one set of chromosomes (23 in humans)
-All gametes are genetically different