Revision Homework

Cell Structures

Nucleic Acids

DNA

Purines

Pyrimidine

2 rings

1 ring

Adenine

Guanine

Cytosine

thymine

DNA replication

STEP 1: The DNA is untwisted and unzipped by DNA helicase

STEP 2: Free nucleotides attach to the complimentary base

STEP : 3 DNA polymerase joins the backbone together and forms 2 stands of DNA

organelles

Golgi apparatus

lysosomes

flagella

Smooth endoplasmic rectillium

cytoskeleton

rough endoplasmic rectillium

centrioles

involved with separation of chromosomes during cell division. also play a role in movement of flagella

help provide strength and support to the cell. it also determines the cell shape. it is involved with the movement of cells and holds organelles in place.

allows a cell to move or to transport substances across it's surface

Packages and modifies proteins and makes lysosomes.

contain digestive enzymes, they are kept separate from the cytoplasm by the surrounding membrane but can be used to digest invading cells or to destroy the cell when it needs to be replaced

membrane bound organelle involved with the transport and synthesis of lipids, steroids and hormones. does not have ribosomes.

membrane bound organelle involved with the transport and synthesis of proteins which have been made in the ribosomes, it is continuous with the nucleus.

releasing a protein

STEP 1: Instructions to make the protein are in the DNA in the nucleus, as a gene on a chromosome.

STEP2: An mRNA copy of the gene is made in the nucleus.

STEP 4: The mRNA attaches to a ribosome

STEP 3: The mRNA leaves the nucleus through a nuclear pore.

STEP 5: The ribosome assembles the protein.

STEP 6 : The assembled protein in the RER is pinched off in a vesicle and transported to the Golgi. It fuses with the Golgi membrane and the contents are released into the Golgi

STEP 7:The Golgi packages and modifies the protein

STEP 8: The proteins are then pinched off by vesicles and send to the cell membrane where they are released from the cell