Bio paper 2 inheritance variation and evolution

Nucleus

Part of a cell where all the genetic info is found

DNA

A polymer made of 2 strands forming a double helix found in the nucleus and makes up chromosomes

Chromosomes

Long molecules of DNA that contain a large number of genes . These are in pairs one from each parent. We have 46 chromosomes in each body cell and 23 in each gamete (sex cell)

Where is the dominant alleles

They are always shown in the phenotype

homozygous

alleles of a gene are the same

heterozygous

alleles of a gene are different

what can a punnet square be used to show

to show what allellles someone is likely to inherit from their parents

what is polydactyl and what is it caused by

extra fingers/toes and is caused by a dominant allele , so only one parent needs to pass on the allele

cystic fibrosis

caused by recessive allelle so both parents must pass on an allelle for the child to have the disease.

what is it called when a person carries one allele for a recessive disease

called a carrier , they can pass it on but wont have the disease themselves

what is embryo screening

is testing an embryo to see if it has a particular condition . it is often used in IVF the embryos are tested and a family will decide whether to implant it or not

why people allow embryo screening

help to stop people suffering , parents can decide whether or not to keep the baby based on the results of the test

why people dont allow embryo screening

risk of miscarriage, not reliable , decision hard to make , expensive , religious and ethical reasons

mitosis

forms 2 genetically identical body cells . it is used for growth/repair . cell parts are grown , then the DNA replicates and then the cell divides

genome

the entire genetic material of an organism

genes

short sections of DNA on a chromosome that contain a code for a particular sequence of amino acids to make a specific protein

allele

a version of a gene

recessive allelles

are only shown in the phenotype if there are 2 copies

genotype

set of alleles for a characteristic

phenotype

physical characteristics of a person due to the environment and genotype

variation

differences in features of different people . can be inherited, environmental or a combination of both

sex chromosomes for female

XX

sex chromosomes for male

XY

gene therapy

using genes to treat or prevent disease . in the early stages of testing and has mixed results

benign tumour

growth of abnormal cells that contained in 1 area . they dont invade other parts of the body

cancer

uncontrolled growth and division of a cell by mitosis

malignant tumour

caancer , invade neighbouring tissues and can spread to other parts of the body , as cells can break off and travel in the blood

asexual reproduction

an organism makes a genetically identical copy of itself formingg a clone . 1 parent , no joining of gametes , uses mitosis only

sexual reproduction

where the sex cells (gametes) from a male and female organism fuse together to form a zygote . it gives variation . 2 parents , uses meiosis to form the gametes

evolution

a change in the inherited features of a population over time . happens by natural selection

natural selection by Charels Darwin

• there is variation in a species caused by random mutation

• gives some individuals a survival advantage

• they can then reproduce and pass on their genes

• the amount of individuals with this feature gradually increases

mutation

a change in the dna . they can cause new proteins to be made , which can change characteristics

what are fossils

remains of organism that lived millions of years ago

how do fossils form

• animal/plant is buried in sediment

• hard parts do not decay

• eventually the bones are replaced by minerals

species

a group of individuals with similar genes that are able to breed with eachother to produce fertile offspring

extinction

there are no remaining individuals of a spcies alive . may be caused by a new predator , a new disease , new competitor or changes in the environment

speciation

evolution of a new specie from an existing one

how is spciation done

1. species are separated by geographical barrier

2. the environments are different in the 2 separated areas

3. mutation occurs

4. those that are better adapted survive and reproduce

5. favorable alleles are passed on

6. eventually the 2 populations are unable to breed successfully with each other and have fertile offspring

genetic engineering

is cutting out useful genes from one organism and inserting them in another

steps involved in genetic engineering

1. enzymes are cut out required gene

2. gene is inserted into a vector

3. vector is used to insert gene into required cells in nucleus

4. genes are transferred t cells of organism in the early stage of development so they develop with the desired characteristics

what are crops called that have genetic engineering

GM

negative of genetic engineering

full effect on human health may not yet be known

positive of genetic engineering

usually better yields

what is a vector

carrier of dna/gene

into cell / other organism

selective breeding

human breed plants/animals for particular genetic characteristics

how to selective breed

1. choose parents with desired characteristic

2. breed together

3. from their offspring ones with desired characterisitic are bred together

4. continue over many generations

negatives of selective breeding

could lead to inbreeding , lead to disease or inherited defects. more expensive for farmers as they have to pay higher vet bills and may get less income from the animals

classification -carl linnaeus

Living thing is can be put into groups depending on their structure or characteristic

The following group: Kingdom phylum class order family genus species

How are organisms named?

By the binomial system of genus and species

What is good about the classification system?

It means everyone uses the same name and the genius gives some idea of ancestry

Evolution tree

You can show evolutionary relationships closely related to animals have a common ancestor that split off more recently

Three domain system developed by Carl Woese

Organisms divide into IKEA which is the primitive bacteria in its extreme conditions then bacteria which is true bacteria eukaryote which is plants, animals, fungi, and protest