Here are the key types of point mutations: - Base substitution: Replacement of one base or nucleotide with another. This can sometimes cause a change in the protein made. - Silent mutation: A base substitution that does not cause a change in the protein expressed by a gene, such as when different codons code for the same amino acid. - Missense mutation: A base substitution that results in a different amino acid being incorporated into the protein. This often impairs the protein's function. - Nonsense mutation: A base substitution that creates a stop codon, causing premature termination of protein synthesis. This usually results in a nonfunctional protein. So in summary, point mutations are single base changes that

1. From Peas and fruit flies to humans…

3. What is a genome???
 All the genetic information (genes) that
make up an organism

4. What makes us
human?
 Analyze human
chromosome…
 Karotype
 Picture of all the chromosomes
in an organism
 Autosomes
○ CHROMOSOMES 1-44 (pairs 1-
22)
○ Autosomal chromsomes
 Sex chromosomes
○ Determine a person’s sex (male
XY or female XX)
○ Chromosome 45 and 46 (set 23)

6. Pedigree Charts
 Shows relationships within a family
 Genetic counselors use these to infer the
genotypes of family members
 Look at each generation different symbols
used

8. Disorders can be recessive or
dominant

10. Recessive disorders
 Disorder phenylketonuria (PKU)
 Caused by an autosomal recessive allele
on chromosome 12
 People with this disorder lack the enzyme
to break down phenylalanine (amino acid
found in milk and many other foods)
 In newborns, this causes a build up of
phenylalanine in tissues during the first few
years of life and lead to mental retardation
 Newborns are commonly tested for PKU and
then put on a low phenylalanine diet if they have
the disorder

11. Autosomal Recessive Allele
 Tay-Sachs Disease
 Recessive allele in Jewish families of central and
eastern Europe ancestry
 Lack the enzyme to break down lipids in neural cells
○ Lipid accumulation in brain cells
 Leads to nervous system break-down and death in the
first few years of life

12. Autosomal Recessive
Disorders
 Cystic Fibrosis
 Do not have the gene that
regulates mucus production
 Excess mucus in lungs,
digestive tract, and liver
 Increased susceptibility to
disorders
 Lung transplants usually
needed after childhood

13. Autosomal Dominant
Disorders
 You will express disorder if
you are homozygous or
heterozygous dominant for
that trait
 You also have higher
chances of passing onto
your children
 Dwarfism (achondroplasia)
 Huntington’s Disease
 Nervous system disorder

14. Co-Dominant Alleles
Disorders
 Sickle cell anemia
 1/500 African Americans have
the disorder
 Co-dominant allele
 Causes blockages in blood
vessels, preventing oxygen from
getting to other cells and tissues
 Beneficial in central and east
Africa because it helped destroy
malaria
 If you had SCA, your body would
destroy the sickle cells to protect
itself and in the process, destroy the
malaria parasite as well

16. Sex-Linked Disorders
 Many sex-linked genes are
found on x-chromosome
 Many genetic disorders
are sex-linked
 Males have just ONE x
chromosome, so whatever
the X chromosome is
carrying (dominant or
recessive) will be
expressed
 Fathers can pass it to their
daughters and the disorder
can show up in the
daughters sons

17. Sex-linked Disorders
 Red-green Color-blindness
 1/10 men
 1/100 women
 Hemophilia
 Two important genes on x-chr control
blood clotting
 Person with disorder can die from minor
cuts
 Recessive allele in either gene can cause
it
 Duchenne Muscular Dystrophy
 Caused by defective version of a gene for
a muscle protein
 Progressive weakening and loss of
skeletal muscle1/3000 males

18. Sex-linked genetic practice
problem
1. In humans the gene from normal blood clotting, H, is dominate to the gene for
hemophilia, h. This is a sex-linked trait found on the X chromosome. A woman with
normal blood clotting has four children. They are a normal son, a hemophiliac son,
and two normal daughters. The father has normal blood clotting. What is the
probable genotype for each member of the family?
2. In humans, the genes for colorblindness and hemophilia are both located on the X chromosome
with no corresponding gene on the Y. These are both recessive alleles. If a man and a woman,
both with normal vision, marry and have a colorblind son, draw the Punnett square that
illustrates this. If the man dies and the woman remarries to a colorblind man, draw a Punnett
square showing the type(s) of children could be expected from her second marriage. How
many/what percentage of each could be expected?
3. A man with normal vision is XY. What kind(s) of gametes (sperm) can he produce?
4. Any woman with normal vision could be XX or XX'.
Since this woman has a colorblind son (genotype X'Y), she has to be XX' (a carrier).
What kind(s) of gametes (eggs) can she produce?

19. Sex Influenced Traits
1. Baldness in humans is a dominant, sex-influenced trait. This gene is on the autosomes, not the
sex chromosomes, but how it is expressed is influenced by the person’s sex (due to hormones
present, etc.). A man who is BB or Bb will be bald and will be non-bald only if he is bb. A
woman will only be bald if she is BB and non-bald if she is Bb or bb (it’s almost like B is
dominant in males and b is dominant in females). Actually, because of the influence of other
sex-related factors, most women who are BB never become totally bald like men do, but
rather, their hair becomes “thin” or sparse. If two parents are heterozygous for baldness, what
are the chances of their children being bald? Use a Punnett square to illustrate this. Note:
because the sex of a person does make a difference in how the gene is expressed, you need
to set this up as a dihybrid cross to account for the sex of the children
2. A non-bald man marries a non-bald woman. They have a son and a daughter. If the son
becomes bald, what are the chances that his sister will, too? Use a Punnett square to show
this cross.
3. A non-bald man has to be XYbb. What kind(s) of gametes (sperm) can he produce?
4. Any non-bald woman can be XXBb or XXbb. The bald son could be XYBB or XYBb, but since
the father is XYbb, we know the son cannot be XYBB (remember the first problem?). The son
has to be XYBb, therefore this mother has to be XXBb (if she was XXbb he couldn't have a B).
What kind(s) of gametes (eggs) can she produce?
5. A woman’s mother is bald, but her father is not. Her older brother is rapidly going bald. She is
an acrobat who hangs by her hair. Should she change her profession before she goes bald,
too? Use a Punnett square to show this.
6.

20. DNA Review
The 2 Fates of DNA
Protein Synthesis
DNA Replication
(when cell is doing is
(if cell enters cell
normal job-in G1
division…S-phase)
phase of cell cycle)

22. DNA Facts
 All living things have DNA
 Prokaryotes-DNA in cytoplasm,
simple
○ Contain extra DNA called
PLASMIDS
 Eukaryotes-DNA in nucleus,
complex
 DNA codes for the same 20 amino
acids in ALL living things
 It is the UNIVERSAL code..all
organisms have the same A,T,G
and C bases and the same 20
a.a., just arranged differently

23. 5
The DNA backbone
PO4
 Putting the DNA
backbone together base
5 CH2
 refer to the 3 and 5 ends O
4 1
of the DNA C
3
○ the last trailing carbon O
2
–O P O
Sounds trivial, but…
O base
this will be 5 CH2
IMPORTANT!! O
4 1
3 2
OH
3

24. Anti-parallel
strands
 Nucleotides in DNA
backbone are bonded from
phosphate to sugar 5 3
between 3 & 5 carbons
 DNA molecule has
“direction”
 complementary strand runs
in opposite direction
3 5

25. Bonding in DNA
hydrogen
bonds
5 3
covalent
phosphodiester
bonds
3
5
….strong or weak bonds?
How do the bonds fit the mechanism for copying DNA?

26. Base pairing in DNA
 Purines
 adenine (A)
 guanine (G)
 Pyrimidines
 thymine (T)
 cytosine (C)
 Pairing
 A:T
○ 2 bonds
C:G
○ 3 bonds

27. Copying DNA
 Replication of DNA
 base pairing allows
each strand to serve
as a template for a
new strand
 new strand is 1/2
parent template &
1/2 new DNA
○ semi-conservative
copy process

28. Let’s meet
the team…
DNA Replication
 Large team of enzymes coordinates replication

29. Important Enzymes
 DNA Helicase
 Unzips original DNA strand
 DNA Polymerase
 Adds nucleotides to the
unzipped sides
 DNA Ligase
 Attaches/glues DNA
fragments together on one
of the new copies

30. How does DNA replicate
itself?
 Template mechanism
 What is a template???
○ PowerPoint presentations….
 Like the negative of a photograph
 DNA Replication
 Process of copying the DNA molecule
○ What phase of the CELL CYCLE?
 S-phase….
 2 strands of double helix separate (Unzips)
 Each strand acts as a negative for making the
new complementary strand
 Nucleotides line up one by one following base
pairing rules
 Enzymes (DNA Polymerase and DNA Ligase)
link nucleotides together to form 2 new DNA
strands called the daughter strands

32. Fate #2: Protein Synthesis
 You already know about this…central
dogma of Biology
 Just need to know your key players…

33. The Protein Synthesis Team
 DNA
 mRNA
 tRNA
 rRNA
 Codons
 Anticodons
 Amino acids
 Proteins
 Introns
 Exons

35.  DNAmRNAprotein
 DNA TRANSCRIBES to
mRNA
 Process is called
transcription
 mRNA TRANSLATES to
proteins
 Process is called
translation
 mRNA actually makes
amino acids, which come
together to make proteins

36. DNAmRNAamino acids/polypeptide chain
(Proteins)
 DNA codes for an RNA strand
 The every 3 bases on the RNA
strand code for a specific amino
acid
 CODON: three sequential bases
that code for a specific a.a. (20
a.a. total)
 Amino acid are strung together to
make a protein (primary structure)
 Change DNA will change RNA
which will change amino acids,
which change protein

38.  Transcription
DNAmRNAProtein
 Different form of the same
message
 DNA makes single
stranded RNA (U replaces
T)
 RNA leaves nucleus
 Translation
 Translate from nucleic acid
language to amino acid
language
 Uses codons, 3-base
“word” that codes for
specific a.a.
○ “code” for an amino acid
 Several codons make a
“sentence” that translates
to a polypeptide (protein)

39. Start Stop
Codons Codons
 AUG  UAA
 UGA
 UAG

40. Three Types of RNA
 mRNA
 tRNA
 rRNA

41. Three Types of RNA… #1
 mRNA (messanger RNA)
 RNA transcribed from DNA template
 Modified in nucleus before if exits
○ RNA splicing: process in which Introns are removed and
exons re joined together to make a continuous coding
mRNA molecule
 Introns
○ Internal non-coding regions of DNA and mRNA
○ Space fillers/jibberish
○ They are cut out of mRNA before it is allowed to leave the
nucleus
○ Process is called RNA splicing (processing)
 Exons (MOST important part of DNA)
○ Coding region of DNA and mRNA that will be translated
(Expressed)
○ VERY important part of mRNA…it is carrying the message
from DNA (def can’t cut this out)

42. Three Types of RNA…#2
 tRNA (transfer RNA)
 The interpreter
 Translate 3-letter base
codes into amino acids
 Carries anti-codon on
one end (three letters
opposite of what is on
mRNA)
 Carries amino acid on
other end
 Anti-codon recognizes
codon and attaches

43. Three Types of RNA…#3
 rRNA (ribosomal RNA)
 Found in ribosome
 Ribosome composed of 2
subunits:
○ Small subunit for mRNA to
attach
○ Large Subunit for two tRNAs to
attach
 “P” site: holds the tRNA
carrying the growing
polypeptide chain
 “A” site: holds the tRNA that
is carrying the next a.a. to be
added to the chain
 When stop codon (UAA, UAG,
UGA) is reached, translation
ends and polypeptide is
released

52. Mutations
 Occur when there is an error in DNA
replication
 Def: Change in genetic material
 Mutagens
 Physical or chemical agents that cause
mutations
○ Ex: high energy radiation (x-ray or UV)
○ Ex. Chemicals (that are similar to DNA but
cause incorrect base pairing)

53.  Mutation
 Any change in the nucleotide sequence of
DNA
 Large or small
 2 Main types
 Point Mutation
○ Base Substitutions
 Frameshift Mutation
 Insertions or deletions

54. Base Substitution
 Replacement of one base or nucleotide with
another
 Usually do not change amino acid
 Sometimes causes a change in the protein
made
 Silent Mutation
 When a substitution does not cause a change in the
protein expressed by a gene
 Remember some codons represent the same amino
acid
 Example: GAA and GAG both code for Glu

55.  Point Mutation
A point mutation is a simple change in one base of
the gene sequence. This is equivalent to changing
one letter in a sentence, such as this example,
where we change the 'c' in cat to an 'h':
Original: The fat cat ate the wee rat.
Point Mutation: The fat hat ate the wee rat.

56. Insertion or Deletion
 Nucleotide is removed or added
 More disastrous
 mRNA is read as triplet codes
 Adding/removing bases changes these three
letter codes
 Codons downstream from insertion/deletion will
be regrouped and probably code for a non-
working protein
 Result: FRAMESHIFT MUTATION
 Shift the “reading” frame of the genetic message

57. Frameshift mutation
 Original: The fat cat ate the wee rat.
 Frame Shift: The fat caa tet hew eer at.

59. Chromosomal Mutations
 Involve changes in the number or
structure of the chromosome

60. Chromosomal Disorders
 Mechanics of meiosis (where we separate
chromosomes) is usually pretty good
 But nobody’s perfect…mistakes happen….
 Most common problem…
 Nondisjunction: when homologous
chromosomes fail to separate properly
 Literally means “not coming apart”
 If this occurs, ABNORMAL #s of chromosomes
may find their way into gametes and a disorder
of chromosome number may result

61. Nondisjunction
 If one of the gametes with an ABNORMAL
# ends up getting fertilized, MAJOR
problems!!!
 Trisomy: “three bodies”
○ Occurs when an autosomal chromosome fails to
separate during meiosis
 When do chrm separate?
- Anaphase I and Anaphase 2
○ One gamete ends up with an extra copy of a
chromosome and then the fertilized zygote ends
up with 3 copies of a chrm instead of 2
○ Example: Downs Syndrome

64. Down Syndrome
 Extra copy of chromosome 21
 1/800 baby’s are born with this
disorder
 Produces mild to severe
retardation
 Increased susceptibility to
diseases, slower development,
and higher frequency of birth
defects
 How can one little extra copy
cause so many problems?
 Scientists are still trying to figure that
out…now that they have used gene
mapping and identified all the genes
on chromosome 21, they can begin
experimenting on this problem

65. Chromosomal Mutations
 May change location of
genes on chromosome
 Include:
 Deletions: loss of part of
chromosome
 Duplications: produce
extra copies of parts of
chromosome
 Inversions: reverse
direction of chromosome
 Translocation: when one
chromosome breaks off
and attaches to another

67. Mutations
 NOT always harmful
 Some alter a protein in a beneficial
way that may help species in a
specific environment
 If mutation is present in organisms
gametes, it may be passed off to off-
spring
 Mutations are the ULTIMATE source
for GENETIC DIVERSITY!!!

68. What is biotechnology?
 Here are some hints…

69. Biotechnology
 Manipulation of living organisms or their
parts to produce useful products
 Main use is to improve human health
and food production
 Seedless fruits
 Make insulin

70. Genetic engineering
 The transfer of genes or pieces of DNA
from one organism into another
organism
 New DNA is a combination of pieces from
two different organisms…called
recombinant DNA
 Used to introduce new characteristics
into organisms and populations
 Gentically Modified Organisms GMOs

71. How to make recombinant
DNA
 Use DNA from complex organism (human) and
transfer to a simple organism (bacteria)
 Uses a PLASMID
 Small circular DNA in bacteria
 It is called a VECTOR when used in genetic
engineering

74. Genetic Engineering
 Positive/benefits  Negatives/Cons
 Make medicine like  Unknown long term
insulin and vaccines effects if ingested by
plentiful and humans
inexpensive  Harm native, natural
 Improves crop plants species
like corn and rice  Cross pollination
○ Grow faster and between GMOs and
stronger wild plants resulting in
○ Resist disease and unwanted hybrids
insects (mockingjays!)
○ Genes can be added  ***Decreases genetic
to add more vitamins
variation
to plants