Molecules of life Flashcards
Why are there different amounts of mitochondria in cells?
- The number of mitochondria in the cyptoplasm of a cell depends on the activity of the cell. This is because respiration occurs in mitochondria.
- Cells such as liver or muscle cells have large amounts of mitochondria. This is because the liver carries out many functions and muscles cells need to contract.
- Both types of cells therefore need lots of energy.
What are ribosomes and where are they located?
Ribosomes are smaller than mitochondria and are also found in the cyptoplasm. They are too small to be seen with a light microscope and are the site of protein synthesis.
What does the nucleus contain?
Genes
Each gene:
- Is a section of a chromosome made of DNA.
- Codes for a particular protein.
What is DNA made of?
DNA is made of two strands coiled to form a helix, each strand containing chemicals called bases. There are four different types of bases, with cross links between the strands formed by pairs of bases. Each gene contains a different sequence of bases.
Where are proteins made?
Proteins are made in the cyptoplasm but DNA cannot leave the nucleus. This means that a copy of the gene needs to be made that can leave the nucleus and carry the code to the cyptoplasm.
What are the bases?
A, T, C and G.
What are the complementary base pairs?
A-t and G-C.
How does the DNA base code control which protein is being made?
The DNA base code controls which protein is made. This is because the base sequence in the DNA codes for the amino acid sequence in the protein. Each amino acid is coded for by a sequence of three bases.
What happens to the code needed to produce a protein?
It is carried to the ribosome by a molecule called messenger RNA or mRNA.
Which proteins are made the most?
Enzymes, which can control the activity of the cell.
How did Watson and Crick build the model of DNA?
By using data from other scientists. Two of the important pieces of data they used were:
- Photographs taken using x-rays which showed that DNA had two two chains wound in a helix.
- Data indicating that the bases occur in pairs.
When did they discover the structure of DNA.
Watson and Crick worked out the structure of DNA in 1953 and shared the Nobel Prize for this discovery in 1962. There is often a delay between a discovery and the award of prizes beacuse other scientists need to check the discovery to make sure it is correct.
