bio paper 2- inheritance and variation

meiosis

non identical cells

sexual reproduction

gamete fusion

mitosis

identical cells

asexual reproduction

no gametes

sexual reproduction involves

fusing of gametes (sperm and egg cells)

homozygous

two copies of the same allele for a trait

allele

different forms for the same gene

heterozygous

two different alleles for a trait

genotype

combination of alleles for a trait

phenotype

physical expression of the genotype, shown charectaristics.

chromosome

long molecule found in the nucleus of cells made from DNA

gene

part of a chromosome that codes for a protein

what leads to variety in offspring?

the mixing of genetic information in sexual reproduction.

genome

all the genetic information of an organism. It consists of nucleotide sequences of DNA.

advantages of sexual reproduction

produces variation

gives survival advantage

advantages of asexual reproduction

one parent needed

faster than SR

organisms that produce by both methods

~malarial parasites asexually in human, sexually in mosquito

~plants produce seeds sexually, but asexual from runners, or bulb division in daffodils

variation

differences in characteristic

variation is due to

the genes they have inherited

the environment in which they develop

mutation

a mutation is a change in DNA sequence

very rarely

mutations can lead to a new phenotype

selective breeding

the process by which humans breed plants and animals for particular characteristics.

process of selective breeding

choose parents with the characteristic, breed them, continue breeding offspring until characteristic is regular.

advantages of selective breeding

disease resistance

animals that produce more

disadvantages of selective breeding

can lead to inbreeding

reduces variation

clone

asexually produced, genetically identical to parent.

tissue culture (cloning)

using small groups of cells from parts of a plant to grow identical plants.

cuttings

older simple method involving a branch from the parent plant cut off, and the stem planted in compost.

embryo transplant

cells split apart from developing animal embryo before they become specialised, then identical embryo into host mothers.

adult cell cloning

nucleus removed from an unfertilised egg cell

nucleus from an adult cell in inserted into the egg cell

electric shock forces egg tio divide into embryo

now they contain the same genetic info. boomshakalaka.

consequences of inbreeding

leads to disease and defects

genetic engineering

modifying the genome of an organism by introducing a gene from another organism.

polydactyly

caused by a dominant allele

cystic fibrosis

caused by a recessive allele

ordinary human body cells

contains 23 pairs of chromosomes

female

XX sex chromosomes

males

XY sex chromosomes

DNA

is made up of two strands forming a double helix

pair bases

C + G ¦¦ T + A

gregor mendel

who developed understanding on genetics

DNA

is a polymer of nucleotides

DNA contains

four different nucleotides

proteins are

polymers of amino acids

the order of amino acids

determines the shape which determines the function

on ribosomes

proteins are synthesised

carrier molecules

bring amino acids to add protein chain, when it’s complete it fold to a shape and function.

archaea

primitive bacteria

bacteria (three domain system)

true bacteria

eukaryota

protists, fungi and animals

alfred russel

theory of evolution by natural selection

antibiotic resistance

resistant bacteria evolving rapidly and reproducing quickly.

biotic

food, predators, pathogens, competition

abiotic

light intensity, wind intensity, moisture, ph of soil, oxygen