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1. Deoxyribose Nucleic Acid

1.1. a molecule that holds genetic information

1.1.1. controls the characteristics of an organism

1.1.2. able to store necessary information, replicate itself and control cellular reactions

1.2. Watson and Crick

1.2.1. used x-ray to produce images of the DNA and worked out

1.2.1.1. distance between atoms

1.2.1.2. size of the atoms

1.2.1.3. angle of bonds

1.2.2. proposed the double helix model for DNA molecules

1.3. structure

1.3.1. nucleotide - basic unit

1.3.2. hydrogen bonding - between bases

1.3.2.1. Adenine + Thymine

1.3.2.2. Cytosine + Guanine

1.3.3. contain phosphate group, pentose sugar and nitrogenous base

1.4. triplet code

1.4.1. three bases make up the code for one specific amino acid

2. Gene & alleles

2.1. there is always a dominant and a recessive allele

2.1.1. mendelian traits

2.1.1.1. one allele always dominant

2.1.2. non-mendelain traits

2.1.2.1. incomplete dominance

2.1.2.1.1. e.g. Rr = pink

2.1.2.2. codominance

2.1.2.2.1. e.g. BW = speckled (white and black)

2.1.2.3. polygenic

2.1.2.3.1. more than one gene determining a trait

2.1.2.4. epstasis

2.1.2.4.1. when one gene determines the presence of a trait

2.2. phenotyoe

2.2.1. traits physically present in an organism

2.3. genotype

2.3.1. permutation of alleles

2.3.1.1. homozygous

2.3.1.2. heterozygous

2.4. punnett squares

2.4.1. shows the possible outcomes of fertilisation

2.5. pedigrees

2.5.1. similar to a family tree that shows the genotype of a family regarding a specific trait

2.6. a unit of hereditary information

3. cell divisions

3.1. before, chromosomes are stored as chromotins

3.2. mitosis

3.2.1. for growth, repair and cell replacement

3.2.2. interphase, prophase, metaphase, anaphase, telephasis, cytokinesis

3.2.3. results in two identical daughter (somatic) cells

3.2.3.1. 46 chromosomes

3.2.3.1.1. 2 sex chromosomes

3.2.3.1.2. 44 autosomes

3.2.3.1.3. diploid number 2N

3.2.4. occurs in all organs

3.3. meiosis

3.3.1. occurs in sex organs

3.3.1.1. ovary

3.3.1.2. testes

3.3.2. for fertilisation and variations in offsprings

3.3.3. 23 chromosomes

3.3.3.1. haploid number N

3.3.4. gametes

3.4. homologous chromosomes

3.4.1. same in length

3.4.2. have the same centromere in the same position

3.4.3. genes in the same position

4. Mutation

4.1. a change occurs in the original DNA sequence

4.1.1. localised change of a gene (base sequence)

4.2. large scale change of larger sections of genes or chromosomes

4.3. types of mutations

4.3.1. substitution

4.3.2. insertion

4.3.3. deletion

4.4. consequences

4.4.1. silent mutation

4.4.1.1. no change in protein structure

4.4.2. missense mutation

4.4.2.1. one new amino acid

4.4.3. nonsnese mutation

4.4.3.1. stop codon

4.4.4. frame shift

4.4.4.1. change in amino acid sequence

4.4.4.1.1. only resulted by deletion or insertion

5. replication

5.1. semi-conservative

5.2. 1. parent DNA molecules begin to "unzip"

6. protein synthesis

6.1. transcription

6.1.1. 1. enzyme RNA polymerase unzips two strands of DNA

6.1.2. 2. one strand is replicated

6.1.3. 3. complementary bases of selected strand is copied as RNA polymerase called mRNA

6.2. translation

6.2.1. 1. mRNA enters a ribosome int he cytoplasm

6.2.2. 2. ribosome sticks amino acids together

6.2.3. 3. tRNA beings in amino acid and mRNA provides order information to make the right protein

6.2.4. 4. polypeptide chain eventually makes a protein