Chapter 8: Heredity DNA DNA-characteristics:

• Hydrogen bonds

• Double Helix

• Sugar-Phosphate backbone

• Starts are made of nitrogen gases.

• Adenine, Thymine, Cytosine, and Guanine

• Complimentary bases, A-T and C-G. Genetic material Genetic material is found in the cell nucleus, and controls what happens in the cells. Genetic material is a different name for DNA, the DNA is the genetic material. Genes contain information about how the human body is to develop and function.  46 DNA chromosomes 23 pairs with the same gene type, in one pair of chromosomes one comes from your father and one from your mother. A chromosome is a DNA molecule that is bound with proteins. Gene: Gene is what carries the inherited characteristics, a gene is attached to a part of the chromosome. Genome: All genes and rests of genetic material found in the organism. Protein Synthesis Two phases of protein synthesis. Transcription and translation.

1. Transcription The DNA strands are separated by enzymes and alter copied. This copy is called m-RNA in which Thymine is replaced with Uracil. M-RNA is a code that is to be delivered to the t-RNA in the ribosome to then create proteins. The m-RNA then leaves the nucleus trough the cell pores and travels to the ribosome where the translation happens.

2. Translation The protein is made according to the m-RNA code. In the ribosome the t-RNA transports the corresponding base to the code of the m-RNA. The bases are forged into triplets bonding together to create a specific amino acid. A chain of amino acids is what makes a protein.

Different proteins

• Enzymes Make chemical elements happen.

• Transport protein Transport substances around the body

• Structural proteins Builds cells and skin tissue.

• Antibodies Defence proteins, a part of the immune system.

• Muscle Proteins Provide movement. Mutations When new gene combinations are formed mutations tend to occur leading to the formation of completely different genes. Mutations are mistakes that happen during the protein synthesis, in which the DNA copy is made incorrectly which changes the order of the bases causing wrong amino acid to form.

1. Substitution – is substation of the first base where a “T” becomes an “A” making the whole triplet incorrect. AAT instead of TAC.

2. Insertion – is insertion of an extra base “T” in the genetic sequence. And the triplet becomes TTA. And this changes the code of all triplets that follow.

3. Deletion – deletion of the fist base in the sequence, where the triplet is then changed to ACG and not TAC, the “G” is the following base after C which forms a triplet due to the deleted T base. Changed gene -> Changed protein. Two types of mutation.

4. Gene Mutation Occurs during DNA replication, A wrong base or the wrong number of bases and the protein is made incorrectly. May prevent the formation of proteins as well. Such damage is usually repaired by a polymerase; however it can cause cancer when it happens in somatic cells, or give new heritable characteristics when it happens in germ cells.

5. Chromosome mutations Involving the whole part of a chromosome. Happens during meiosis where the DNA strands cross over.

• Pieces of chromosomes can end up in the wrong place or a chromosome can end up in the wrong daughter cell. In this way some germ cells with 22 chromosomes and some with 24 chromosomes are formed.

• This can give Turner syndrome and downs syndrome.

Increased mutation risk

• UV radiation

• X-rays

• Radioactive sources

• Some toxic substances such as tobacco smoke, organic solvents and drug abuse.

Cell division Each gene pair can be combined in 4 different ways, each in different gametes. In total with all the 23 different chromosomes there will be 8,4 million combinations.Meiosis

• Gender formation. Results in gametes- egg and sperm cells. The egg cells and sperm cells get only half the number of chromosomes as a cell. The offspring must have the same number of chromosomes as the parent.

• Four sex cells

• Crossing over

Mitosis Happens in all cells except egg cells and sperm cells – called somatic cells. Daughter cells are exactly the same number of chromosomes.

• Two daughter cells

• DNA copy before split

• Cell reproduction Inheritance Gregor Mendel was the first person to experiment on inheritance, he did the experiments on green and yellow peas in his garden. Inheritance is all about genetics and genes. Dominant and Recessive genes play big part of what characteristics you inherit from your parents.

• Dominant genes camouflage the effect of a recessive gene, a dominant gene is marked with CAPITAL LETTERS. Whilst recessive genes are the one being camouflaged by the dominant gene and are marked with lower case letters.

• Genes can be homozygous or heterozygous. Homozygous is a gene with the same letter meaning same gene pair such as “AA” or “aa”. Heterozygous are the ones with different letters meaning different gene pairs “Aa”.

• Additionally Genotypes and Phenotypes are important, a genotype shows the gene combination (Gg or GG) while the phenotype shows the gene characteristic (yellow peas, blue eyes, red hair) Sex linked inheritance. Sex linked inheritance refers to a gene on a sex chromosome. The sex chromosomes are what decide what gender the child will be. (X is female an XY is male)

• Example: red-green blindness is more common for men than women, roughly 10% of men and only 1% of women have this sex-linked gene. The gene for red-green blindness is found on the X-chromosome. The Y-chromosome which is much smaller is missing this gene.

• If a man inherits this recessive gene, it will show itself, because there is no gene type like it on the Y-chromosome. However, if a women inherits it, the dominant X-chromosome can camouflage the gene and make her the carrier. Punnet Grind

Evolution Changes in climate and environment along with DNA variations cause evolution and genetic change.

• Survival of the fittest by Charles Darwin, he said that animals and organisms all must adapt in order to survive.

• Theory of evolution is the most documented theory ever made. It forms the basis of all biological understanding today, and even though it has changed through the years the basis has remained the same.

• Theory of evolution involves how life changes and evolves. Meaning there is a structural change in genetics.

1. Genetic variation- mutations

2. Heredity- characteristics are inherited to the next generation.

3. Overpopulation of the offspring

4. Natural Selection

5. Formation of new species