2. GENETICS
• Field of Biology that studies how
characteristics are transferred
from parent to offspring
• Begins, chronologically, with the
work of Austrian monk Gregor
Johann Mendel in the 1850-60s.
• by mrjurkiewicz on Nov 29, 2010
3. MENDEL: EDUCATION
• In fact, Mendel was a welleducated scientist
• Studied physics and
mathematics at the
Olmütz Philosophical
Institute at the University
of Vienna, beginning in
1851
• by mrjurkiewicz on Nov
29, 2010
5. LOCATION OF DNA IN
A CELL
• Chromatin is a complex of DNA and
protein, and is found in the nucleus
of eukaryotic cells.
• Histones are proteins that are
responsible for the first level of DNA
packing in chromatin
• The chromatin network in the
nucleus of a cell will coil up tightly
during cell division and form
individual chromosomes.
6. • Chromosomes are always
duplicated during this process (2
sets of identical genetic information to
ensure each cell receives identical
genetic info to the parent cell during
cell division).
• A duplicated chromosome consists
of 2 chromatids attached to each
other by a centromere.
• Each chromatid consists of several
genes.
• Genes consists of a long DNA strand.
10. is the process in which traits are passed
from parents to offspring
is the study of heredity
11. CHARACTERS OR TRAITS ARE RESEMBLANCES OR
DIFFERENCES WHICH CAN BE:
Seen e.g.
eye colour
flower colour
Tested for e.g.
blood groups
colour blindness
12. LET’S REVISE:
• Genes:
control the characteristics of living organisms
are carried on the chromosomes
14. • Genes are in pairs
• Genes controlling the same characteristics occupy identical positions on
corresponding chromosomes
• The gene pairs control one characteristic
gene for
eye colour
gene for
nose shape
gene for
making insulin
15. The genes of a corresponding
pair are called alleles
Alleles are alternative
forms of the same gene
Gene
Homologous chromosomes have the same
length and carry the same gene sequences
17. MUTATIONS
• A mutation is a change in a gene
• A mutation can only be inherited in it occurs in a sex cell
• Effects of mutations can be:
•
Positive
•
Negative
•
Neutral
18. CHROMOSOME MUTATIONS
.Deletion – loss of a piece of a chromosome
. Translocation – a piece of one chromosome
breaks off and reattaches to a nonhomologous
chromosome
Nondisjunction – chromosome fails to
separate from its homologue during meiosis
19. GENE MUTATIONS
• Point Mutation – one nucleotide is changed in the DNA sequence
•
Substitution
•
Deletion
•
Insertion
20. GENE MUTATIONS
• Insertion – one or more
nucleotides are added to a gene
• Substitution – one nucleotide
replaces another
22. MOLECULAR GENETICS
• How many of each type of
chromosome does a cell have?
• TWO! (Chromosomes
come in pairs.)
23. VOCABULARY
• Alleles – several
alternate forms of a
gene that cause
different traits
• Example: one allele may
cause blonde hair, while
another causes black
24. ALLELES
• Organisms ALWAYS have
two alleles (one on each
chromosome)
• Alleles can be either
dominant or recessive
25. ALLELES
• Letters are used to represent alleles
• Capital letters = dominant genes
• Lowercase letters = recessive genes
27. ALLELES
• Since organisms have two of each
type of chromosome (with one
allele on each), genes must be
represented by two letters
• Examples: HH, Hh, or hh
30. GENETICAL TERMINOLOGIES:
• Homozygous – two of the
same alleles
• Homozygous dominant - two
dominant alleles
• Homozygous recessive – two
recessive alleles
32. EXAMPLE
• Long necks in giraffes are
dominant to short necks (N
and n)
• Genes vs. displayed trait
33. GENETICAL TERMINOLOGIES:
• Genotype – genetic makeup of
an individual (example: Nn or
nn)
• Phenotype – observed
characteristics (example: long
or short neck)