B3 - Genes and Proteins Flashcards
What are the functions of the cell membrane, cytoplasm, mitochondria and nucleus ?
cell membrane – controls what enters and leaves the cell
cytoplasm – where many of the reactions of the cell happen
mitochondrion – aerobic respiration happens here
nucleus – contains DNA
How do chromosomes, genes and DNA link together?
- Inside nucleus of cells - 23 pairs of chromosomes.
- Each chromosome = one long molecule of DNA.
- In each DNA molecule, there are shorter sections of DNA. These are different genes.
What do you need different proteins for?
• growth, which involves making new cells
• repair of damaged tissue, by replacing dead cells with new cells
• building structures such as muscle, bone, skin, hair, enzymes, hormones, antibodies, and haemoglobin
Why does genetic code control your characteristics?
- genetic code controls how enzymes are made.
- Enzymes control all the chemical reactions that go on in your cells. So the genetic code controls all cell activity.
- As a consequence it controls most of your characteristics.
What determines the function of a cell?
Different types of cells have different functions and therefore need different proteins, including enzymes. Hence in any cell only some of the full set of genes are used, and the rest are switched off. The genes in a cell that are switched on determine the function of the cell.
How was the structure of DNA figured out by scientists?
Watson and Crick used data from the work of other scientists to work it out. Rosalind Franklin obtained X-ray data which showed that a DNA molecule consisted of two chains wound in a double helix. Watson and Crick used her data and help from chemist colleagues to build their model of DNA – a double helix with pairs of bases forming cross- links.
Describe the process of protein synthesis.
• The base pairs ( ATGC) form a code and are ‘read’ in groups of three, or base triplets.
• Each triplet specifies a particular amino acid.
• The sequence of the triplets of bases on a section of DNA specifies the sequence of amino acids in a protein.
• mRNA, carries a copy of the coded instructions in a gene out of the nucleus.
• The mRNA is a single-stranded molecule. It is a copy of one strand of a length of DNA.
• The mRNA goes to a ribosome. Here it governs how the amino acids are assembled into a protein.
• The amino acids are assembled into long chains.
• The sequence of amino acids in the protein governs how the protein will fold up into a particular shape.
Name a structural protein and its job.
Collagen - skin, bones, cartilage, tendons, ligaments, and walls of blood vessels contain it
Name a protein hormone and its job.
Insulin - made in the pancreas. Travels in
blood stream to target organs, muscles, and liver. Regulates blood sugar level.
Name a carrier protein and its job.
Haemoglobin - in red blood cells. Carries oxygen from lungs to respiring cells.
Name some types of proteins.
Structural protein
Carrier protein
Hormones
Enzymes
What other jobs can proteins do?
• antibodies
• receptors for hormones on membranes of target cells
• channels in cell membranes.
