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Unit 1- Key Area 4 - DNA and the production of proteins
1-Describe the structure of a DNA
Double stranded/ double helix.
molecule.
Made of sub-unit called nucleotides.
Each nucleotide consists of:
- phosphate
- desoxyribose sugar
- a base (adenine, thymine, guanine or
cytosine).
Bases on each strand form complementary
pairs.
2-What holds a DNA strand together? A bond between the sugar of one nucleotide
and the phosphate of the adjacent
nucleotide.
3-What type of bond holds the two
Hydrogen bonds.
strands together to form the double
helix?
4-What is determined by the base
The genetic code. In proteins, the base
sequence?
sequence determines amino acid sequence.
5-Complementary rule
A-T and G-C.
Protein synthesis
1-What are the chemical elements
C-H-N-O and some sulfur.
found in proteins?
2-Structure of proteins is determined DNA sequence which itself determines the
by…
order of amino acids.
3-Name of the type of bond between
Peptide bond.
amino acids
4- Give 5 examples of types of
Enzymes: speed up chemical reactions.
proteins and their function
Hormones: carry chemical messages around
the body (e.g. insulin)
Antibodies: recognize molecules of invading
organisms to defend the body against
disease.
Structural: connect and support tissues (e.g.
collagen).
Receptors: participate in cell signaling.
5-Where does protein synthesis take
In ribosomes in the cytoplasm.
place?
6-What carries the sequence
mRNA= messenger RNA
information from where it is stored
(i.e. in the nucleus) to where it is
needed (ribosome)
7-Characteristics of RNA
- Single stranded
- sugar is ribose
- Uracil (U) is found in place of thymine (T).