REVIEW – Back of books 1. Name 3 differences between sexual and asexual reproduction. 2. Give 2 examples of asexual reproduction. 3. What is a variation? 4. What is the difference between continuous and discontinuous variation? 5. Give an example of each type of variation.

Genetics LO: Describe the basic process by which genetic information is passed from one generation to the next

Inheritance and Genes Why are we like our parents? It’s all to do with the genes we have inherited.

Living Things All living things are made of cells All cells contain a central nucleus The nucleus is the control centre for the cell.

Cells

More Cells

Lets take a closer look This cell has a number of ribosomes, mitochondria and other un-named objects (5 yellow ones) It has only one nucleus. The nucleus has a number of chromosomes

Chromosomes

What are chromosomes? Chromosomes are made up of DNA molecules. The DNA molecules have genes coded on them Highlight the organism  cell  chromosome  DNA sequence in your book IMPORTANT

What are genes? Genes are sections of DNA molecules which contain coded information. Genes determine how we will develop. Genes control factors such as eye colour, facial features, hair type, height.

Human Genetics Humans are diploid. That is our chromosomes come in pairs, each with the same sequences of genes, except the sex-pair – called XY. Each feature is therefore controlled by a gene on each chromosome in the pair.

DNA 1ZvsYDTxc8 1ZvsYDTxc8 oDJ8FWA oDJ8FWA 6.31/2.29

DNA The structure of DNA is the same in all living things It looks like a twisted ladder, known as a double helix. DNA is made of repeating units called nucleotides. A nucleotide is made of 3 parts, a sugar, a phosphate and a base. Highlight the red text from above in your SciPad page 129

DNA In your books page 129 on the diagram of a nucleotide….. ◦ Colour the phosphates one colour ◦ Colour the sugars another colour ◦ Colour the ‘A’s and the word adenine below a different colour ◦ Colour the ‘T’s and the word thymine ◦ Colour the ‘G’s and the word guanine ◦ Colour the ‘C’s and the word cytosine

DNA Structure The side of the helix are made up of the sugar and the phosphate. These are linked together by the nucleotide bases. There are four nucleotide bases. ◦ Adenine (A) ◦ Thymine (T) ◦ Cytosine (C) ◦ Guanine (G)

The chemical make-up of the bases means that adenine always bonds with thymine and cytosine always bonds with guanine. This is called the “complementary base- pairing rule” (A) adenine = thymine (T) (C) cytosine = guanine (G) Complementary base-pairing rule Hint: straight letters go together (A-T), curved letters go together (C-G)

SciPad pg 129 Complete the questions and the base- pairing sequence.

Next Lesson Cell reproduction and karyotypes