Topic 1 - Genes And Enzymes Flashcards
What does a plant cell have that an animal cells doesn’t?
Rigid cell wall
Vacuole
Chloroplasts
Nucleus?
Contains DNA that controls what the cell does.
Cytoplasm?
Where the chemical reactions happen.
Cell membrane?
Holds the cell together.
Controls what’s in and out.
Mitochondria?
Reactions for respiration.
This releases energy that the cell needs to work.
Rigid cell wall?
Made of cellulose, gives support for the cell.
Vacuole?
Contains cell sap.
Chloroplasts?
Where photosynthesis occurs. They contain chlorophyll.
4 things that are in animal and plant cells?
Nucleus
Cytoplasm
Cell membrane
Mitochondria
Features of a bacterial cell?
Chromosomal DNA
Plasmids
Flagellum
Cell wall
Role of chromosomal DNA?
Controls the cells activities and replication. It floats free in the cytoplasm.
Role of plasmids?
Small loops of extra DNA. Contain the gene for drug resistance.
Flagellum role?
Rotates to make the bacterium move.
Structure of DNA?
Two strands coiled together in a double helix. The two strands are held together by chemical bases. Adenine, cytosine, guanine, thymine.
Base pairing is A-T and C-G.
What is a gene?
A section of DNA and the sequence of bases in a gene code for a specific protein.
How did franklin and Wilkins work out the structure of DNA?
They found the helical structure by directing beams of x-rays onto crystallised DNA and looking at the patterns the x-rays formed as they bounced off.
Watson and crick?
Made the model of the DNA molecule where all the pieces fitted together.
Protein synthesis step one?
Transcription. The two DNA strands unzip. The coding strand of the DNA is copied. The DNA acts as a template to make mRNA (ribonucleic acid). This is like DNA but it is one strand made of C, G, A, and U (uracil).
Protein synthesis step two?
Translation. mRNA moves out of the nucleus to the ribosome. The mRNA codes for the order of amino acids in the chain and is read. tRNA carries the amino acids that match the mRNA code to the ribosome. 3 bases (codon) are read at a time. The tRNA is an anticodon so matches to the mRNA codon. The ribosome links the amino acids in the order together to make a polypeptide. This folds into a special shape for the new protein to work.
How are proteins made?
By organelles called ribosomes. DNA is found in the nucleus and can’t get out because it is really big. The cell needs to get the information from the DNA to the ribosome in the cell cytoplasm. This is done by using mRNA which is shorter than DNA but only a single strand. mRNA uses uracil instead of thymine. However uracil still joins to adenine. mRNA is like a messenger between the DNA in the nucleus and the ribosome.
What is a mutation?
A change to an organisms DNA base sequence. This could affect the sequence of amino acids in the protein. This could affect the shape of the protein and it’s function. Mutations can be harmful, beneficial or neutral.
How is a mutation harmful?
It can cause a genetic disorder, e.g cystic fibrosis.
How is a mutation beneficial?
Produce a new characteristic that is beneficial to an organism. E.g. A mutation in genes on bacterial plasmids can make them resistant to antibiotics.
What is neutral about mutations?
Not harmful or beneficial. They don’t affect a proteins function.