Genetics Flashcards
(37 cards)
Sexual reproduction definition
When genetic information is combined from two organisms to produce genetically-different offspring
Fertilisation method
Male gamete fuses with female gamete to make a soy gore
Zygote contains full set of chromosomes
Zygote undergoes cell division and becomes an embryo
Embryo inherits characteristic from both parents as it is a mixture of chromosomes from both parents
Meiosis method
It duplicates its DNA
Chromosomes line up in centre of cell
Chromosomes in each pair came from both parents of organism
Chromosomes are pulled apart so new daughter cells contain only one copy of each chromosome
This creates genetic variation in the offspring (as each cell has a mixture of mother’s and father’s chromosomes)
The chromosomes line up again in both daughter cells and undergo mitosis, creating 4 daughter cells
Sexual reproduction advantages
Creates genetic variation in a population (so at least some individuals will survive when environment changes)
Leads to natural selection and evolution as species become better adapted to their environment
Sexual reproduction disadvantages
Takes time and energy (so less offspring)
Two parents are required
Asexual reproduction advantages
Produces lots of offspring quickly (so colonises an area quickly)
Only one parent is needed so can reproduce anytime
Asexual reproduction disadvantages
No genetic variation between offspring in population (so whole population will be affected from environmental change)
All bases in DNA
Adenine
Thymine
Cytosine
Guanine
Shape of DNA
Double helix
DNA molecule structure
Made up of nucleotides
Nucleotides made up of pentose sugar, phosphate backbone and base
Complementary base pairs are connected by weak hydrogen bonds
Chromosomes definition
Long coiled-up molecules of DNA
Gene definition
Section of DNA that codes for a particular protein
Extracting DNA from fruit cells method
Mash strawberries or kiwi and put them in a beaker containing detergent and salt
Detergent will break down cell membranes (releasing them)
Salt will make DNA stick together
Filter mixture to get froth and insoluble bits of cell out
Gently add ice-cold alcohol to filtered mixture
DNA will come out of mixture as insoluble in cold alcohol
Fish DNA out with glass rod
What controls protein synthesis in a cell?
DNA
Protein definition
Chains of amino acids that controls a function in the body
Base triplet definition
Sequence of three bases that decides what amino acid is used in that turn in a gene
Mutation definition
Rare, random change to an organism’s base sequence that can be inherited
Transcription method
RNA polymerase binds region of non-coding DNA in front of gene
2 DNA strands unzip and RNA polymerase moves along one of strands of DNA
It uses coding DNA in the gene as template and makes mRNA and ensures DNA and RNA base pairs are complementary
It moved out of the nucleus and joins with a ribosome
What replaces thymine in messenger RNA?
uracil
mRNA structure
polymer of nucleotides that’s shorter than DNA and only single-stranded
RNA polymerase definition
Enzyme involved in joining together RNA nucleotides to make mRNA
Why is transcription required?
DNA in the cell nucleus is too large to move out of the nucleus
Translation method
Order and what amino acid is brought is decided by codons in mRNA
tRNA with complementary anticodon to codons of mRNA brings amino acids in correct order
Amino acids are joined together by ribosome, making a polypeptide chain (protein)
Role of non-coding DNA in protein synthesis
RNA polymerase needs to bind to a region of non-coding DNA in front of a gene
