Dna and inheritence

What is dna

A code for anything, individual to each person

Dna structure

2 long chains of alternating sugar and phosphate - double helix

What base pairs with guanine

Cytosine

What base forms with adenine

Thymine

How to form a triplet code

Read down one of the chains the order of bases froms the triplet code

What do triplet bases code for

An Amino acid

What do amino acid chains form

Proteins

Genetic profile

Used to compare similarities between dna samples

How does genetic profiling work

A DNA sample is cut into short pieces which are then separated into bands

Genetic profiling - uses

• criminal cases

• Paternity cases

• Comparing speices for classification

Advantages of genetic profiling technology

• dna evidence is reliable

• Used to identify genetic disorders early

Disadvantages of genetic profiling

• Storage of DNA profiles can be seen as an invasion of privacy

• Theft from dna databases

Gametes

Sex cells

Genotype

Alleles represented by letters eg. BB, Bb, bb

Pheneotypes

The physical look/appearance of the organisms

Heerozygous

2 different alleles of the same gene. Hh

Recessive

Masked by dominant allele in phenotype

Dominant allele

Physical appearance of being

Homozygous dominant

Both alleles are the same (both dominant/capital)

Homozygous recessive

Both alleles are the same (recessive/lower case)

punnet square results

Set out as Ratios

Chromosome number in humans

46

Male sex chromosomes

XY

Female sex chromosomes

XX

Determination of sex

For each fertilisation there is a 50% chance the offspring will be male or female

Genetic modification

Allows genetic material from one organism to be transferred to the dna in another organism

Advantages of genetic modification

• genes for disease resistance can be transferred to crop plants to increase yeild.

• Herbicide resistant genes can also increase yield as herbicides can be used to kill competing plants (weeds)

Disadvantages of genetic modification

• creation of super weeds if the herbicide resistant genes are taken up by weed.

• Unknown health effects of eating modified organsims

• Unknown long term effects of modifying genomes