genetics Flashcards
Explain the role of meiotic cell division
- produces 4 daughter cells which are haploid (half number of chromosomes (23))
- these are gametes (gametes are genetically different)
Describe DNA as a polymer made up of
a) repeating unit of nucleotides - sugar and phosphate groups, one of four bases on sugar
b) two strands coiled to form a double helix
c) strands linked by series of complementary base pairs, joined with hydrogen bonds
Describe the genome as the entire DNA of an describe the genome and the gene
a) genome = all the DNA in an organism
b) gene = section of a DNA molecule - codes for a specific protein
Explain how DNA can be extracted from fruit
- mash strawberries put in detergent and salt solution beaker
a) detergent breaks down cell membranes to release DNA
b) salt makes DNA stick together - filter
to get the froth and big - insoluble bits of cell out - gently add ice cold alcohol
- DNA comes out of solution as its not soluble in cold alcohol
a) a stringy white precipitate (solid), fish out with glass rod
Explain why there are differences in the inherited characteristics
as a result of alleles
- dominant alleles beat recessive alleles
- dominant alleles chose which characteristics are present
- differences in characteristics are caused by 2 recessive alleles
explain the term chromosomes
coiled up molecules of DNA, found in nucleus of eukaryotic cells
explain term allele
different versions of genes
explain term dominant
-capital letters
-always expresses itself even with recessive
explain term recessive
-lower case
-supressed in presence of dominant
explain term homozygous
same alleles
explain term heterozygous
different alleles
explain term genotype
genetic information
explain term phenotype
physical feature
explain term gamete
sex cells, sperm and egg
explain term zygote
fertilised egg
- when a male gamete fuses with female gamete to produce a fertilised egg
what is monohybrid inheritance
inheritance of a single characteristic
Describe how the sex of offspring is determined at fertilisation
- girls have XX, boys have XY (Y causes male characteristic)
- eggs, one X chromosome
- sperm, either X or Y chromosome
- so equal chance of boy or girl
— sex determination depends on the sperm that fertilises egg carries and X or Y chromosome
what are most phenotypic features a result of
multiple genes not single gene inheritance
- different combinations of alleles give different phenotypes
describe causes of variation that influence the phenotype
a) genetic variation - organisms have different alleles, different characteristics as a result of mutation and sexual reproduction - > difference in phenotype
b) environmental variation - different characteristics cause by an organisms environment (acquired characteristic), characteristics an organism gets in life
Discuss the outcomes of the Human Genome Project and its
potential applications within medicine
the HGP wanted to find all human genes
- genes help predict diseases they might get
a) helps predict and prevent diseases - get advice to stop disease
b) testing and treatment for inherited disorders - faulty alleles, identify disorder quick to get better treatment
c) new and better medicine - shows genetic variations, can design new drugs tailored to people with particular genetic variation, shows how well existing drug works (how people respond to it too), how the disease affects us to understand it and develop more effective treatments
- downsides= stress, geneism, discrimination
State that there is usually extensive genetic variation within a
population of a species and that these arise through mutations
-mutations are changes to base sequence of DNA
- mutations are the main source of genetic variation
- when in a gene, results in allele or different version of gene
how badly do genetic mutations effect people
- most have no effect on phenotype
- some have small effect of phenotype
- rarely a single mutation will hugely affect phenotype
