Genetics Flashcards
Describe 2 advantages of asexual reproduction
- Requires 1 parent (No need to find a mate)
- Offspring can be produced very quickly due to the reproductive cycle
Explain a disadvantage of asexual reproduction
No genetic variation, meaning if environmental conditions become unfavourable, the whole population may be affected, less chance of survival.
Explain an advantage of sexual reproduction
Introduces genetic variation into the population, meaning if there was an environmental change, some species would have more chance of survival.
Describe 2 disadvantages of sexual reproduction
- Takes long periods of time, less offspring can be produced
- Two parents needed, can be a problem for isolated individuals
Describe the cells produced by meiosis.
Produces 4 genetically different daughter cells, called gametes. They are haploid cells (Half genetic material).
Why are haploid cells produced via meiosis.
So when they fuse with another gamete (sex cell), the cell will have the full genetic material of a normal cell.
Describe the structure of DNA
They are polymers made up of nucleotides (A sugar, phosphate and base). Two strands of DNA are coiled into a double-helix shape.
How are DNA strands held together to form a double helix shape
The strands are linked by a series of complementary base pairs
joined together by weak hydrogen bonds
Describe the word Genome
The entire DNA of an organism
Describe the word Gene
A section of DNA which codes for a protein
Explain the stage of protein synthesis, Transcription
RNA polymerase binds to non-coding DNA located in
front of a gene.
Double helix structure of DNA uncoils leaving exposed bases.
RNA polymerase produces a complementary mRNA
strand from the coding DNA of the gene.
mRNA leaves to enter cytoplasm via a nuclear pore.
Explain the stage of protein synthesis, Translation
mRNA attaches to a ribosome.
Each three bases in the mRNA is a codon, 1 codon codes for 1 amino acid. tRNA brings amino acid the the mRNA, along with anti-codons to compliment the codons on the mRNA. Chain of amino acids form, known as a polypeptide. The tRNA detaches, and the polypeptide chain folds up, forming a protein
Define the terms: A) Chromosome
B) Allele
A) Chromosomes in the nucleus are made from genes which are made from DNA
B)Alleles are different versions of the same gene
Define the terms: A) Dominant
B) Recessive
A) An allele which is always present (Shown) even if only one copy is present.
B) Only expressed if the individual has two copies and does not have the dominant allele of that gene
Define the terms: A) Homozygous
B) Heterozygous
A) Homozygous alleles are both identical for the same characteristic, for example AA or aa.
B) Heterozygous alleles is when an individual has different alleles for a particular gene.