Inheritence, Variation And Evolution Flashcards
What are the 2 types of cell division
Mitosis
Meiosis
What is mitosis
Results in the formation of 2 genetically identical daughter cells from one cell. It’s used in asexual repreducfion
What is meiosis
This results in the formation of 4 genetically non identical daughter cells from one cell. It’s used in sexual reproduction
What happens in sexual reproduction
The fusion of male and female gamete’s. Cells in reproductive organs divide by meiosis to create gametes. Gametes contain half the number of chromosomes found in all body cells
What happens in asexual reproduction
Involves 1 parents with no gametes joining. It happens using the process of mitosis where 2 identical cells are formed from 1 cell. There’s no mixing of genetic information. It leads to clones which are genetically identical to eachother and the parent. For example bacteria
What are the features of sexual reproduction
1) 2 parents
2) cells divide by meiosis
3) offspring is non identical
4) male and female gametes fuse
What are examples of sexual gametes
Sperm and egg cells are gametes in animals
Pollen and ovum cells contain the gametes in flowering plants
What are the features of asexual reproduction
1) cells divide by mitosis
2) off spring are clones
3) only one parent
4) no gametes fuse
What happens when cells divide to form gametes
Copies of the genetic information are made
The cell divides twice to form 4 gametes each with a single set of chromosomes
All gametes are genetically different from eachother
Gametes Join at fertilisation to restore the normal number of chromosomes: the new cell divides by mitosis. The number of cells increases. As the embryo develops, cells differentiate
What organisms reproduce asexually
Strawberry plants reproduce asexually
Daffodils reproduce asexually
What is the genome
The entire genetic material of an organism
What is DNA
A polymer made up of 2 strands of making a double helix structure
What are genes
A small section of DNA. Genes code for a sequence of amino acids which combine to give a specific protein
What are chromosomes
Long strands of DNA are coiled up to form chromosomes . They contain many genes. Human body cells contain 23 pairs of chromosomes one of each pair coming from each parent
What is the smallest to largest
DNA-gene-chromosome-nucleus-genome
What is the importance or the human genome
Gene identification- identifying genes linked to different disorders allowing those of risks to make informed lifestyle decisions
Improving our understanding of the causes of inherited disease and how we should be treating them
What is the importance of the human genome (2)
Human history-investigating human evolutionary history including how humans migrated in the past
How many chromosomes do human body cells have?
46 chromosomes (23 pairs)
What are mutations
A permanent change in the nucleotide of DNA. Mutations happen continuously and normally only slightly affect protein or don’t affect them at all. Occasionally a mutation may change the structure/shape of a protein
What are the outcome of mutations
The outcome of mutations is almost always detrimental to protein function. For example in enzymes the substrate may no longer be able to bind to the active site. In structural proteins their strength may be reduced
What’s a survival advantage
More rarely a mutation may give a survival advantage such as resistance to an antibiotic in bacteria. These mutations can be benefitted and represent the foundations of evolution by natural selection
What is an allele
The different forms of a gene. Humans have 2 alleles for each gene. 1 from each parent
What is a dominant gene
Only one out of the 2 alleles is needed for it to be expressed and for the corresponding phenotype to be observed
What is a recessive gene
2 copies are needed for it to be expressed and for the corresponding phenotype to be observed
