National 4 and 5- DNA
The nucleus
All of the cells genetic information is found in the nucleus and is contained in
threadlike structures called chromosomes.
Chromsom es
N ucleus
This genetic information:
1. controls of all the cells activities
2. determines the cells characteristics
Every living organism has a characteristic number of chromosomes and each one
of their cells contains an identical copy of these chromosomes.
This is important to ensure that every cell has all of the characteristics of the
organism.
This characteristic number is known as the chromosome complement and varies
from species to species.
Structure of chromosomes
Chromosomes are made from tightly coiled molecules of a chemical substance
called DNA.
DNA
All the genetic information of an organism is contained within it’s DNA
DNA is a code that determines the sequence of amino acids in a protein
DNA stands for DeoxyriboNucleic Acid
DNA consists of two strands which are arranged in a twisted coil
structure known as a double helix. Each of these strands has a backbone
to which molecules called bases are attached.
 There are four different bases which are arranged into a code of genetic
information.
 A section of DNA containing a single piece of genetic information is called
a gene.
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A gene is a section of a chromosome that contains a single piece of
genetic information
The function of DNA
The genetic information contained within the DNA can be thought of as a list of
genetic instructions that the cells uses to make proteins.
Proteins are made from amino acids joined together into chains.
There are 20 different types of amino acids and the differences between
proteins are due to the amino acids they contain.
DNA is a sequence of bases and each set of three bases codes for a specific
amino acid. This tells the cell what order to add the amino acids in when making
a protein e.g.
Messenger RNA (mRNA)
Is the molecule that carries a copy of the code from the nucleus, to a ribosome,
where a protein is assembled form amino acids.
Check point B1
Level 4 E&O
I can use my understanding of how characteristics are inherited to solve simple genetics
problems and relate this to my understanding of DNA genes and chromosomes
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Nat 4
DNA, genes and chromosomes
Genes are located on chromosomes in the nucleus. Genes are made of DNA which carries
instructions to make proteins. Each individuals DNA is unique. Genes are passed on from
parent to offspring.
Nat 5
4 DNA and the production of proteins
a. Structure of DNA: double-stranded helix held by complementary base pairs. DNA
carries the genetic information for making proteins. The four bases Adenine, Cytosine,
Guanine and Thymine (A, C, G and T) make up the genetic code. The base sequence
determines amino acid sequence in protein.
b. Messenger RNA (mRNA) is a molecule which carries a complimentary copy of the code
from the DNA, in the nucleus, to a ribosome, where the protein is assembled from amino
acids
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