GCSES Genetics

• Meiosis: cell division where 4 haploid cells are created
• Chromosomes: strands of DNA
• DNA: a chemical and a polymer of nucleotides.
• Dna is also called deoxyribonucleic acid
• Genes are small sections of DNA
• A and T bases pair up as they form 2 hydrogen bonds
• C and G bases pair up as they form 3 hydrogen bonds
• The backbone makes the 'upright' of the DNA ladder and is made of alternating sugar and phosphate
• The four bases are rings on the DNA ladder that are chemical units. Hydrogen bonds form between these.
• The four bases are made of adenine, cytosine, guanine and thymine
• Each base pairs with another specific base (complementary base pairing)
• Gregor mendel is the father of genetics
• Gregor mendel experimented on pea plants
• Gregor mendel discovered the laws of inheritance
• Gregor mendel made an early prediction of genes
• The Y chromosome is a mutant
• There is a 50% chance of being a boy or a girl and your sex is determined by the male sex cell
• Alleles: different forms of gene that code for different variation of a characteristic
• Homozygous: pair of alleles are the same
• Heterozygous: pair of alleles are different
• Dominant: allele always expressed
• Recessive: allele only expressed with 2 of the same type
• Genotype: description of pair of alleles for a characteristic
• Phenotype: physical expression of alleles
• Blood type is determined by marker molecules on the outside of your red blood cell
• Codominance: form of dominance where alleles in a heterozygous pair both affect the phenotype
• Colour blindness is a sex linked disorder and is when cone cells in the retina don't work properly
• Colour blindness affects 8% of men
• Colour blindness affects 0.5% of women
• Haemophilia is a sex linked disorder where the body's ability to make blood clots is impaired
• Carrier: someone who carries one faulty allele but doesn't have the disease
• Locus: position of gene on chromosome
• Cystic fibrosis: an inherited diesase caused by a recessive allele where people have problems with their lungs and digestive system
• Continuous variation: feature able to be measured and is given a value from a range
• Discontinuous variation is a feature that can't be measured and is a distinct option.
• mRNA: copy of required gene that codes for the needed protein
• Codon: triplet of three bases
• mRNA is single stranded, has ribose sugar in the backbone and has bases A, G, C, U (uracil instead of thymine)
• In transcription, DNA is unwound by the enzyme, RNA polymerase
• tRNA: carries amino acids to the ribosome during translation