B3 Genetics

sexual reproduction

• variation in offspring

• requirement to find a mate

asexual reproduction

• no variation if offspring

• rapid reproductve cycle

• no need to find a mate

meiosis

cell division the reduces the number of chromosomes by half it produces four non identical haploid sex cells (gametes)

structure of DNA

• polymer made of two strands

• strands are coiled to form a double helix shape

how are strands of DNA linked together

• complementary base pairs

• bases are joined together by weak hydrogen bonds

what are nucleotides in DNA

• building blocks of DNA

• Each nucleotide consists of a sugar, phosphate group, and one of the for bases

what are the four base in DNA and how do they pair

• A and T

• C and G

genome

• the genome is the entire DNA of an organism

• It contains all the genetic information needed for growth, development and functioning

gene

a gene is a section of a DNA molecule

It codes for a specific protein that carries out a particular function in the body

how to extract DNA from fruit

• mash up fruit

• add salt and washing liquid

• heat

• filter and keep liquid

• cool

• add cold ethanol

how does order of bases affect proteins

order of bases determines order of amino acids in a protein

role of amino acids in proteins

• building blocks of proteins

• sequence of amino acids determines portends structure and function

how are amino acids ordered

• DNA are red in codons (groups of 3)

• Each codon codes for a specific amino acid

what happens after amino acids are assembled

• the chain of amino acids folds into a specific shape

• the shape determines the protein function, such as forming enzymes

why is the shape of a protein important

• shape of protein = function of protein

• enzymes the shape determines their active site and ability to catalyse reactions

stages of protein synthesis

1. dna instructions: DNA has a code that tells the cell how to make proteins.

2. mRNA copy: The cell makes a copy of the DNA code called mRNA

3. mRNA to ribosomes: The mRNA travels to the ribosome.

4. amino acids: tRNA brings the correct amino acids to the ribosome.

5. protein chain: The ribosome links the amino acids together to form a protein.

6. folding: the protein chain folds into a specific shape to work properly

3.9 +3.10

Gregor Mendeleev key discoveries

• principles of inheritance through pea plants

• genes come in pairs

• some traits are dominant some are reccesive

chromosome

long coiled structure made of DNA that contains many genes

gene

small bit of DNA that carries code for something

allele

different variations of the same gene (dominant or reccseive)

homozygous

two identical alleles for a gene

heterozygous

two different alleles for a gene

genotype

combination of alleles for a particular gene

phenotype

physically observable trait

gamete

sex cell

zygote

fertilised egg from when two gametes combine

monohybrid inheritance

the study of how one characteristic is passed from parent to offspring (use punnet squares)

how is the sex of an offspring determined

• combination of sex chromosomes from each parent

• females = XX

• male = XY

ABO blood groups

• I^A

• I^B

• i

  I^A + I^A or i = A

  I^B + I^B or I = B

  I^A + I^B = AB

  i + Ii= O

what cause sex linked genetic disorders

• disorders linked to genes on the X chromosomes

• e.g colour blindness, hemophillia

how do sex linked disorders affect females

• female have two X chromosomes

• need two recessive alleles to show the disorder

• with one recessive alleles female are carriers

draw out a punnet square of a 50/50 chance of done having hemophillia

are most phenotype (physical) feature influenced by a single gene or multiple genes

multiple

genetic variation

differences in characteristics due to genetic factors

• mutations

• genes from parents

environmental variation

differences in characteristics caused by an organisms environment

• acquired characteristics like tattoos

human genome project

• global research that mapped out all the genes in the human genome

outcomes of human genome project

• complete DNA sequence

• genetic testing in medicine

• personalised medicine

• gene therapy

what causes genetic variation in a population

mutations