Science B5

Cells are the building blocks of all living things

All cells contain DNA and Organelles

DNA molecules are in the form of a double helix and contain teh genetic code.

Organelles are the different parts of the cell's structure. They do different jobs within the cell and work together to allow cells to perform a specific structure.

Human Cells, most animal cells and plant cells have the following parts:

• Cytoplasm - where most chemical reactions take place
• Nucleus - contains genetic information
• Ribosomes - where protein synthesis takes place
• Cell Membrane - controls movement into and out of the cell

Plants have the following parts:

• Cell Wall - strengthens the cell
• Permanent vacuole - helps support the cell
• Chloroplasts - absorb light energy to make food

During fertilization, a male gamete and a female gamete fuse together to produce a single body cell called a zygote.

Gametes only have half the number of chromosomes as the parent cell, so the zygote that's produced has one whole set of chromosomes.

The zygote then divides by mitosis to produce a cluster of cells called an embryo.

The embryo continues to develop by mitosis to eventually become an adult individual. 

Genes are present on the chromosomes in each cell nucleus

Genes control:

• growth and development in organisms
• the development of characteristics e.g eye color