Transcript Mutations - Montville.net

Human Red Blood Cells
1. Contain the protein, hemoglobin (Hb)
2. O2 binds to Hb = oxygenated blood
3. Red Blood Cells are doughnut shaped cells
Sickle Cell Anemia
1.
2.
3.
4.
RBC’s are “sickled shape”
Hemoglobin protein has been altered -shape has
changed
Cells stick to each other; Oxygen binding capacity has
been altered.
Circulatory problems arise
Why?
Gene Mutation
1. A change in the DNA
2. A change in the sequence of nitrogenous
bases: A, T, C or G
3. Carcinogens can cause the change
Normal Hemoglobin:
Valine-Histidine-Leucine-Threonine-Proline-Glutamic Acid-Glutamic Acid
Abnormal Hemoglobin:
Valine-Histidine-LeucineThreonine-Proline-Valine-Glutamic Acid
Sickle Cell Anemia had change in the polypeptide chain:
Glutamic acid is changed to Valine
Why??????? How can this be??????????????
Change Affects Codon
Normal Hb
Sickle Hb
DNA = CTT
mRNA = GAA = Glutamic
acid
DNA = CAT
mRNA = GUA = Valine
-Proline-Glutamic Acid-Glutamic
Acid-
-Proline-Valine-Glutamic AcidThis results from mutated DNA!
Base-pair substitution = replacement of one nitrogenous base
This is also referred to as a point mutation.
Frameshift Mutations
1. Changes the reading of the DNA
2. Results in the formations of new mRNA
codons
3. Types are: insertion or deletion
Identify the category and
type of mutation affecting this
strand of DNA
1.
AUGCCGUACCUUAUGGCUG
Write the new mRNA codons
that would result.
1.
A
2.
AUGC_GUACCUUAUGGCUG
2.
Remember: These are all gene mutations.
Chromosomal Mutations
Alterations in chromosome
number and/or structure
More Chromosomal Mutations
Deletion
Duplication
Homologous
chromosomes
Inversion
Reciprocal
translocation
Nonhomologous
chromosomes
Figure 8.23A, B
Chromosome Number – set number in a somatic cell, for
example, chromosome number is 4
What will be the number in a gamete cell?
Egg
cell
Sperm
cell
zygote
This is chromosomal mutation
Examples of chromosome numbers
Species
# of chromosomes
Species
# of chromosomes
Fruit fly
8
Human
46
Rye
14
Ape
48
Guinea Pig 16
Sheep
54
Dove
Horse
64
edible snail 24
Chicken
78
Earthworm 32
Carp
104
Pig
40
Butterflies
~380
Wheat
42
Fern
~1200
16
LE 13-10
Key
Maternal set of
chromosomes
Possibility 2
Possibility 1
Paternal set of
chromosomes
Two equally probable
arrangements of
chromosomes at
metaphase I
Metaphase II
Daughter
cells
Combination 1
Combination 2
Combination 3
Combination 4
LE 13-7
Interphase
Homologous pair
of chromosomes
in diploid parent cell
Chromosomes
replicate
Homologous pair of replicated chromosomes
Sister
chromatids
Diploid cell with
replicated
chromosomes
Meiosis I
Homologous
chromosomes
separate
Haploid cells with
replicated chromosomes
Meiosis II
Sister chromatids
separate
Haploid cells with unreplicated chromosomes
A karyotype is a photographic inventory
of an individual’s chromosomes
• To study human chromosomes
microscopically, researchers stain and
display them as a karyotype
– A karyotype usually shows 22 pairs of
autosomes and one pair of sex chromosomes
• Preparation of a karyotype
Blood
culture
Packed red
And white
blood cells
Hypotonic solution
Stain
White
Blood
cells
Centrifuge
3
2
1
Fixative
Fluid
Centromere
Sister
chromatids
Pair of homologous
chromosomes
4
5
Figure 8.19
Let’s look at this Karyotype
• This karyotype shows three number 21
chromosomes
• An extra copy of chromosome 21 causes
Down syndrome
Figure 8.20A, B
• The chance of having a Down syndrome
child goes up with maternal age
Figure 8.20C
Karyotype Lab
1.
2.
3.
You will simulate the karyotyping task.
You will create a karyotype and determine the gender
and developmental status of the baby.
You must carefully cut out all chromosomes and
correctly match them up by:
a. Size of chromosome
b. Location of centromere
c. Banding pattern on chromosome
Beginning the Karyotype
Finished Karyotype
Another Karyotype
Male or Female?