Flashcards in Molecules Of Life Deck (22):
Recall the chromosomes in the nucleus:
Carry coded information in the form of genes
Are made of a molecule called DNA
What is the information in the genes in form of?
Coded instructions called the genetic code
What does the genetic code control?
Cell activity and consequently some characteristics of the organism
What does DNA control?
The production of different proteins
What are proteins needed for?
Growth and repair of cells
Who worked out the structure of DNA?
Two scientists called Watson and Crick
Explain why liver and muscle cells have large numbers of mitochondria?
They have a high energy requirement
Are ribosomes easily seen?
No they are too small to be seen with the light microscope
Where are ribosomes found?
In the cytoplasm and are the site of protein synthesis
Describe the structure of DNA
Two strands coiled to form a double helix, each strand containing chemical bases, of which these are four different types, with cross links between the strands formed by pairs of bases.
Long, coiled molecules of DNA, divided up into regions called genes
Recall that each gene:
Contains a different sequence of bases
Codes for a particular protein
Where are proteins made?
In the cytoplasm
Understand why a copy of the gene is needed
The gene itself cannot leave the nucleus
What are the four bases of DNA
Describe the complimentary base pairs
A - T
G - C
Explain how protein structure is determined by the DNA base code
- the base sequence determines amino acid sequence
- each amino is coded for by a sequence of 3 bases
Explain how the code needed to produce a protein is carried from the DNA to the ribosomes by a molecule called mRNA
1. mRNA constructed from DNA template in nucleus
2. mRNA carries code from original DNA into the cytoplasm and becomes attached to a ribosome
3. Ribosome 'translates' the code on mRNA and constructs a sequence of amino acids
4. Amino acids linked together as a long chain protein,which is released from the ribosomes to carry out its function
Explain how DNA controls cell function by controlling the production of proteins, some of which are enzymes
When a cell needs to produce proteins of a particular type, certain genes will be 'switched on'. These genes and their resulting proteins determine the characteristics of cells.
Describe how Watson and Crock used data from other scientists to build a model of DNA
X-ray data showing that there were two chains wound in a helix
Data indicating that the bases occurred in pairs
Explain why new discoveries, such as Watson and Crick's, are not accepted or rewarded immediately
The importance of other scientists repeating or testing the work