dna and inheritance

a nucleus

chromosomes

dna- deoxyribonucleic acid

the entire genetic code of an organism

adenine thymine cytosine guanine

polymers (large molecules) made up of monomers (smaller subunits) called nucleotides

a nucleotide is made up of a phosphate group, sugar and a base thee sugar and phosphate molecules alternate, with paired chemicals between each strand called bases

the backbone of dna

thymine + adenine guanine + cytosine this is called complementary base pairing

• put strawberries in a bag and crush to a pulp by hand (this breaks apart the cell walls and removes the insoluble part) • put in 5cm³ of dish soap and 2 heaped spoons of salt into the bag (the dish soap breaks down the membranes of the cell and the nucleus) • mix it all up • after 15 minutes, put the bag into a plastic beaker with ice, and on top of the bag • put a cloth over the beaker with an elastic bag (protease is sometimes added to break down protein and destroy any enzymes that could break down the dna) • push down the middle of the j cloth to make a hollow • then, put the mixture into the hollow so it can filter • then take the cloth off and put it in the bin 9.rhen put the filtrate into a cooled test tube, then out the ice cold ethanol into the tube ( cold ethanol helps the dna to precipitate) • then use a wire to lift out the white stringy layer - dna

• it contains 46 chromosomes -it holds and protects dna -the cell membrane protects the nucleus

-a gene is a section of a chromosome -a long strand of chromosomes is called a long coil of dna -chromosomes are made of dna

• it has a double helix structure • bonded together with weak hydrogen bonds • joined together by pairs of bases? base pairs • dna carries code up of base pairs

the difference between organisms of the same species

organisms that can breed together to produce fertile offspring

• genes (inherited from parents in chromosomes) • the environment • both genes and the environment

a characteristic that we can see or measure

something caused by the environment

• mutations (a random change in genes or chromosomes) • sexual reproduction

variation l mutation ( a random change in a gene) l characteristics most suited to the environment (alleles that are responsible for the useful characteristic to be passed on to the next gen) l survive (survival of the fittest) l reproduce l genes passed on to the next generation l mutant genes become more common in the population (over a long period of time)

the two alleles of a gene that an organism has

when the genotype has two lowercase letters

when the genotype has two uppercase letters

when the genotype has one uppercase and one lowercase letter