Human Genetic Mutations
2 Main Types of Mutations
1. __________________________________
2. __________________________________
• What are chromosomes?
Humans have ______________ pairs of chromosomes, with one chromosome from each parent.
The chromosomes are coiled up ______________.
Under normal conditions all of the chromosomes are inherited in tact.
Chromosomal Mutations
• Any change in the ____________________ or ______________________of chromosomes
• Large scale: Affect ____________________ genes
• 5 Types
1. _____________________________
2. _____________________________
3. _____________________________
4. _____________________________
5. _____________________________
•
Chromosomal Deletion
What is it? __________________________________________________________________
What does it cause? _______________________________________________________
•
Chromosomal Duplication
What is it? __________________________________________________________________
What does it cause? _______________________________________________________
•
Chromosomal Inversion
What is it? _______________________________________________________________
What does it cause? _____________________________________________________
•
•
Chromosomal Translocation
What is it? _________________________________________________________________
What does it cause? _____________________________________________________
Nondisjunction-Chromosomes _____________ TO SEPARATE during ________________
•
Nondisjunction
Produces gametes (and therefore a baby) with one missing chromosome or one extra
chromosome
Nondisjunction (in Meiosis II)
Fertilization
Nondisjunction
• Every cell in that baby’s body will have ______ copies of this chromosome instead of________.
• This condition is called ________________________.
• Trisomy 21 = Individual has _____ copies of chromosome # ________
Chromosomal Mutations
• Most chromosomal mutations are ______________________
• If the fetus survives: Tend to cause wide-spread abnormalities
• Example: Down Syndrome
• Down Syndrome
Cause: _______________________________________________
__________ copies of chromosome 21 = ______________________________________
• Genetic Screening - __________________________________________
________________________________
• Karyotypes
A pictorial display of ________________________ chromosomes
from a mitotic cell
Homologous chromosomes- pairs
Chromosomes pairs 1-22 are called ___________________________
Chromosome pair 23 are called the _______________chromosomes
•
•
•
•
•
•
•
•
Klinefelter’s Syndrome
Due to _______________________________
Chromosome makeup is __________________
Creates a sterile male
Turner’s Syndrome
Due to nondisjunction
__________________________- the condition in which there is a missing chromosome.
Sex chromosome make up is ___________ only
Females that will not undergo puberty.
Edward’s Syndrome
Due to nondisjunction
Extra number ____________ chromosome (trisomy 18)
Traits: Low ears, kidney and heart defects
Patau’s Syndrome
Extra number __________ chromosome (trisomy 13)
Traits: Deformed eyes, ears and lips
KEY POINT #1 Too much or too little DNA is bad!
Gene Mutations
Small scale: one ____________ is affected
Any change to the DNA sequence of a gene:
Nucleotides/Bases may be __________________, __________________or ______________________
•
•
Gene Mutations: 2 Types
1. __________________________
2. __________________________
Point Mutation
One base (A, T, C, or G) is substituted for another
Can Cause: Sickle-cell anemia
3 Possible Consequences:
1. ___________________mutations: code for a stop, which can translate the protein
2. ___________________mutations: code for a different amino acid
3. ___________________ mutations: code for the same amino acid
Point Mutation
•
Frameshift Mutation
One or more bases (A, T, C, or G) are added or deleted
Can Cause: Cystic Fibrosis
Caused by:
_______________________: adding a base
_______________________: removing a base
Frameshift Mutation
•
•
•
Causes of Mutations
1. spontaneous
2. occur during DNA replication
3. Caused by _____________________________
i. ________________________ ex: radiation from UV rays, X-rays or extreme heat
ii. _________________________(molecules that misplace base pairs or disrupt the helical
shape of DNA).
Gene Mutations
KEY IDEA: A mutated gene will make a mutated _______________________
•
•
•
•
•
•
•
•
•
•
•
•
•
Example: Sickle Cell Anemia
Normal Red Blood Cell
– Red blood cells shaped like a disc
– ____________________________ (protein) carries oxygen to all parts of the body
Sickle Red Blood Cell
– Red blood cells form an abnormal ________________________ shape
– Hemoglobin (protein) is abnormally shaped
– don't move easily through your blood vessels
– form ______________________ and get stuck in the blood vessels
Mutation located on Chromosome _______________
Effects mostly African Americans
Example: Cystic Fibrosis (CF)
What is it?____________________________________________
Where is it found? ______________________________
Symptoms
– Thick ___________________________in the lungs and digestive track
– Constant lung infections and impaired digestion
Who gets it?
– Most common in Caucasians
Prevalence
– 1 in ~3,000 Americans has CF
– 1 in 23 white Americans carries the mutant allele!
Cause of Cystic Fibrosis (CF)
The “CFTR” gene is mutated
3 base pairs are _____________________________
Mutant protein is missing an __________________________ and cannot fold correctly
Albinism
Due to the lack of the pigment ____________________ (a protein) in the skin, eyes, and hair.
Hemophilia
Disorder that is linked to the sex chromosomes
Missing a protein needed for the blood to ________________
Tay-Sachs Disease
Inability to synthesize an enzyme that prevents _________________buildup in brain cells.
Causes the breakdown of nervous system
Phenylketonuria (PKU)
Inability to code for an enzyme needed for changing the amino acid
____________________________ to tyrosine.
Damages brain cells and causes mental retardation.
Duchenne Muscular Dystrophy
Linked to the sex chromosomes
Results in the progressive ___________________________ and loss of skeletal muscle.
Colorblindness
Carried on the ____________ of the sex chromosomes.
Occurs more frequently in ____________________ than females.
KEY POINT #2 Mutation of a gene = Mutant protein
____________________________ proteins cause the symptoms of the disorder