Chromosomes

Slide 1: 

Cells Chromosomes genes and DNA

Slide 2: 

Aims Understand the relationship between DNA, genes, chromosomes and cells. Know that the nucleus contains chromosomes that control what the cell and therefore how the organism will develop. DNA is the molecule that codes this information and that it is has 4 bases. Can give some use to which a knowledge of genes can be put.

Slide 3: 

quess who?

Slide 4: 

Fertilisation

Slide 5: 

Animal Cell unstained stained

Slide 6: 

Egg, cleaving After several rounds of cell division, the fertilized egg has started its complicated development into an individual During early development a single large cell changes into an embryo consisting of thousands of different cells organized into tissues with 200 different types of cells. The first 12-13 divisions are synchronous.

Slide 7: 

Baby in water sack - amnion

Slide 8: 

specialised cells

Slide 9: 

Levels of organisation Chromosomes genes DNA

Slide 10: 

The two cells (gametes), sperm and egg, each contribute the same amount of chromosomes. In humans this is 23 chromosomes.

Slide 11: 

An amimal cell Note: No chromosomes are visible. We only see them when the cell divides and makes copies.

Slide 12: 

To make the division of nuclear material easier the chromatin condenses. This is when the chromosomes become visible.

Slide 13: 

light microscope

Slide 14: 

The DNA stays in the nucleus (like a reference library

Slide 15: 

Electron microscope

Slide 17: 

Base pairs in DNA bond together to form a ladder-like structure. Because bonding occurs at angles between the bases, the whole structure twists into a helix. DNA A always pairs with T C always pairs with G

Slide 18: 

DNA the double helix

Slide 19: 

DNA This diagram shows the hydrogen bonds between C and G A and T Special enzymes are able to unzip the molecule to make copies of more DNA or RNA which then is read off and codes for proteins

Slide 20: 

DNA replication The DNA is unwound by an enzyme called DNA polymerase. Due to the pairing rule ie A pairs with T G pairs with C Free bases A, T, G and C slot in and two identical new DNA molecules are made

Slide 21: 

Chromosome magnified 20,000X

Slide 23: 

Levels of organisation Chromosomes genes DNA

Slide 24: 

Match the Pairs

Slide 26: 

Chromosomes The chromosomes contain the information to code for the organism. They vary in number and size, as well as banding (genes) from species to species.

Slide 32: 

One reason why it’s important study cells. It can help us make important facts about us The cells from the baby in the water sac are used to count the number of chromosomes.

Slide 34: 

Key words DNA Nucleus Chromosomes Allelle Molecule that makes up the chromosomes and is double helix in shape Part of the cell that controls the cells activities and contains the chromosomes Rod like structures in the nucleus that are made up of genes gene Piece of the chromosome that control a given characteristic eg tongue rolling A form of the gene eye-colour can be brown or blue base One of the 4 molecules in DNA A,T,G and C

Slide 35: 

The body is made up of about 200 different types of _______ which are _______________ to do a certain job. The ____________ is the part of the cell the controls the cell. It is only when the cell is going to divide that the ______________________ can be seen. Human cells contain ________ chromosome arranged in ________, half coming from the mother and half from the father. Each chromosome may contain from 1500 to 600 _________ which appear as bands on the chromosome. The DNA molecule is a ___________________ in shape and consists of _________ bases _____ _____ ______ _____, which pair. cells specialised nucleus chromosomes 46 pairs genes double helix 4 A T G C