Genetics
Page 270 - 282
Key Knowledge
By the end of these lessons you should be able to understand:
• the distinction between a genome, gene and allele
• the genome as the sum total of an organism’s DNA measured in the number of base pairs
contained in a haploid set of chromosomes
• the role of genomic research since the Human Genome Project, with reference to the
sequencing of the genes of many organisms, comparing relatedness between species,
determining gene function and genomic applications for the early detection and diagnosis of
human diseases.
Genes
-
Deoxyribonucleic acid (DNA) the most common genetic material for all organisms.
-
What percentage of their genes match yours?
Another human?
99.9% - All humans have the same genes, but have
variations in sequences to make them unique
A chimpanzee?
98% - Chimpanzees have the closest genetic
makeup to humans
A mouse?
92%
A fruit fly?
44%
Yeast?
26% - Yeasts are single celled organisms, but have
similar genes, such as the gene that enable energy
to be derived from the breakdown of sugars
A weed?
18% - plants have metabolic differences to humans,
but still have similar ‘housekeeping’ genes
Genes
Heredity is the study of inheritance. It looks at the mechanisms and patterns of
inheritance through transmission of coded chemical instruction between
generations.
Genes represent stretches of DNA that make up a ‘unit’ of genetic information
that can be ‘read’ and signal production of a protein.
The DNA sequence is the way in which DNA molecules are put together, and are
what makes individual genes different.
Recap DNA Structure
1. A five-carbon deoxyribose sugar
2. A negatively charged phosphate group linked by phosphodiester bonds
3. A nitrogenous base
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)
Hydrogen Bonds and Base Pairing
Hydrogen bonds hold the double helix together between the opposing pairs of
nitrogenous bases.
What is a hydrogen bond? Write down your answer
The base pairing rule results in complementary
nitrogenous bases being connected by hydrogen
bonds.
Double Helix Activity
Make an origami DNA double helix.
Draw the double helix you have created in your workbooks. You must illustrate:
- The three chemical components to DNA (deoxyribose sugar, phosphate and
nitrogenous bases)
- The correct hydrogen bonds
Chromosomes
DNA and its associated proteins make
up chromosomes
DNA is coiled around histone proteins
to form nucleosomes, then wrapped
into chromosomes
Chromosomal pairs are matched on
size, centromere position and banding
pattern
Karyotypes
The complete set of chromosomes of an
organism.
Note that chromosomes are arranged into
pairs.
Each pair are ‘homologous chromosomes’
because they are the same size and shape
and code for the same genes. However they
may have different alleles.
Humans have 22 autosomal pairs and a pair
of sex chromsomes for a total of 23 pairs or
46 individuals
Identifying chromosomal
disorders
Karyotyping is used to identify anomalies in
that person’s chromosomal make-up. Notably
the addition or subtraction of chromosomes.
Define:
- Monoploidy
- Polypoidly
- Aneuploidy
Identify the error in this individual’s
karyotype, explain how it may have
occurred and the common name of the
condition/syndrome.
Define:
Genes
Genomes
Alleles
The Genome Story
Activity
Create a timeline of the Human Genome:
- From the discovery of genetics
- To the Human Genome Project Completion
Resource:
https://unlockinglifescode.org/timeline
Key Terms:
DNA
Heredity
DNA Sequence
Genes
Genomes
Alleles
Human Genome Project
Double Helix
Hydrogen Bonds
Deoxyribose sugar
Phosphate
Phosphodiester bonds
Nitrogenous Base
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
Nucleotide
Recap Questions
Complete questions 9.1->9.2