Human Heredity Flashcards
What are the two types of mutations?
Gene mutations and chromosomal mutations.
What is a mutation?
A change in the genetic sequence.
What is a gene mutation?
It is a mutation that produces changes in a single gene.
What is one type of gene mutation?
A point mutation.
What is a point mutation?
A mutation that results from changes in one or few nucleotides.
What are the three types of point mutations?
Substitutions, deletions, and insertions.
What is a substitution?
A point mutation that substitutes an amino acid for a wrong one (usually only affects a single amino acid).
What is a deletion (in point mutations)?
A point mutation where an amino acid is deleted (affects every amino acid past the point mutation).
What is an insertion?
A point mutation where an amino acid is inserted (affects every amino acid past the point mutation).
What is another name for a deletion/insertion?
A frameshift mutation.
What is a chromosomal mutation?
A mutation that involves changes in the number or structure of chromosomes.
What are the five types of chromosomal mutations?
Deletion, duplication, inversion, translocation, and nondisjunction.
What is deletion (in chromosomal mutations)?
A chromosomal mutation where a piece of chromosome is lost.
What is duplication?
A mutation that results in an extra copy of genes.
What is inversion?
A mutation where a piece of chromosome breaks off and reattached backwards.
What is translocation?
A mutation were a piece of chromosome breaks off and attaches to another chromosome.
What is nondisjunction?
A mutation that occurs during meiosis when homologous chromosomes fail
to separate.
What does nondisjunction result in?
It results in an abnormal number of chromosomes.
What is polyploid?
A condition that occurs when an organisms has an extra set of chromosomes.
How many copies of an allele do dominant genes need to be expressed?
1
Where, in the chromosomes, is an autosomal disorder found?
The first 22 pairs.
True or false
Both males and females are equally susceptible to inheriting dominant autosomal disorders.
True
What are three examples of a dominant autosomal disorder?
Achondroplasia, Huntington’s disease, and hypercholesterolemia.
What is achondroplasia?
A form of dwarfism that affect the growth of long bones.
What is Huntington’s disease?
A disease that results in progressive loss of muscle control and mental function until death occurs.
When do symptoms for Huntington’s disease start to appear?
Between the ages of 30 and 50.
What is hypercholesterolemia?
A condition characterized by very high levels of cholesterol in the blood which can lead to heart disease.
What is a recessive autosomal genetic disorder?
A genetic disorder that usually requires two copies of alleles before it can be expressed.
True or false
You can be a carrier of a recessive genetic disorder and not show symptoms.
True
What are five examples of a recessive autosomal genetic disorder?
- Phenylketonuria (PKU)
- Tay-Sachs Disease
- Albinism
- Galactosemia
- Cystic fibrosis
Describe phenylketonuria (PKU).
It occurs when you lack the enzymes to break down phenylalanine, and amino acids found in milk and many other foods.
What happens if someone with PKU accumulates too much phenylalanine or amino acids found in milk, ect.?
It builds up in their brain and can lead to mental retardation.
Describe Tay-Sachs disease.
Individuals lack the ability to produce an enzyme that helps break down a chemical found in nerve tissue called gangliosides (a lipid).
True or false
Tay-Sachs disease is more common in Indian families.
False, it is more common in Jewish families.
What happens to someone with Tay-Sachs disease?
Gangliosides build up in their nerve tissues and break down there nervous system, death normally occurs by the age of five.
Describe albinism.
It is caused by mutation and one of several genes that provide instructions for making one of the proteins in the production of melatonin.
Describe galactosemia.
It is a condition in which the body is unable to use the sugar glucose.
What happens if someone with galactosemia has galactose?
It builds up in their system and can lead to damage of the liver, brain, kidneys, and eyes.
Describe cystic fibrosis.
It results in the production of too much mucus, this interferes with breathing and the digestive processes of the pancreas.
True or false
Cystic fibrosis is more common in people whose ancestors came from Eastern Europe.
False, cystic fibrosis is more common in people whose ancestors came from NORTHERN Europe.
Give an example of a codominant genetic disorder.
Sickle cell anemia
Describe sickle cell anemia.
It result from a point substitution, which results in glutamic acid instead of valine in the recipe for the protein hemoglobin.
How does sickle cell anemia affect the body?
The abnormal hemoglobin is not is soluble as the normal form and often sticks together in long strands causing clots.
Why is sickle cell anemia more common in African-Americans?
Because being heterozygous (just a carrier) for sickle cell anemia makes you resistant to malaria.
What is an example of a multiple allele trait?
Your blood type.
What makes people’s blood types different?
The presence of certain proteins on the red blood cell called antigens.
What type of anti-bodies would type A blood produce?
Anti-B bodies
True or false
AB blood has no antibodies.
True
True or false
Type O blood has no antibodies.
False, it has no antigens.
True or false
Type O blood produces both antibodies.
True
What does the genotype for type A or type B blood look like?
A- iAi or iAiA
B- iBi or iBiB
What does the genotype for type AB blood look like?
iAiB
What does the genotype for type O blood look like?
ii
Who discovered sex-linked traits and linkage groups?
Thomas Hunt Morgan
What did Thomas Hunt Morgan choose to work with for his experiments, and why?
Fruit flies because…
• they mature quickly
• they produce lots of offspring
• they only have 4 genes
Describe Morgan’s observation.
He noticed that all females had red eyes, and males had either red or white eyes.
Explain Morgan’s experiment.
• P1 generation
- red eye female x white eyed male
• F1 generation
- all red eyes
- crossed F1 male w/ F1 female
• F2 generation
- 3/4 red, 1/4 whiteWhat are genes located on the same Y-chromosome called?
Y- traits
What are genes located on the same X-chromosome called?
X-linked traits
True or false
Males are more likely to get a recessive genetic disorder.
True
What are 3 examples of sex- linked genetic disorders?
Color blindness, hemophilia, duchenne muscular dystrophy.
Describe hemophilia.
It is when your blood does not clot properly.
Is colorblindness dominant or recessive?
Recessive
Is hemophilia dominant or recessive?
recessive
Describe duchenne muscular dystrophy.
It is a defect in the gene that codes for a muscular protein.
Is duchenne muscular dystrophy dominant or recessive?
Recessive
What does this mean in a pedigree?
◼️
Male
What does this mean in a pedigree?
⚫️
Female
What is X chromosome inactivation?
Since females have two X chromosomes and they only need one, one is randomly used in the other turns into a dense mass called a bar body.
What is a linkage group?
A group of genes located on the same chromosome.
Describe the “linkage group experiment’s” results.
Linkage groups are normally inherited together, but occasionally an offspring does not follow this pattern.
Why are linkage groups sometimes not inherited together?
Because crossing over occurs and mixes them up.
Who did the “linkage group” experiment?
Alfred Sturtevant
What is gene mapping?
A way to determine the distance between genes on a chromosome.
What is the unit used in gene mapping?
Map units
True or false
If two genes are separated 55% of the time, then there are 55 map units apart.
True
What does a chromosomal disorder result from?
Nondisjunction
What is a trisomy?
A didorder that results when individuals have an extra chromosome.
What is a monosomy?
A disorder the results when individuals are missing a chromosome.
What is another name for down syndrome?
Trisomy 21
True or false
Sex chromosome disorders are more severe than autosomal disorders.
False, they are less severe than autosomal disorders.
What are two examples of sex chromosome disorders?
Turner’s syndrome and Klinefelter’s syndrome.
Describe Turner’s syndrome.
It is a monosomic disorder where females tend to not mature sexually and often times are sterile.
Describe Klinefelter’s syndrome.
It is a disorder in which you have an extra X chromosome, and it occurs in males who often are sterile.
What does someone with Klinefelter’s syndrome look like?
They have abnormal body proportions.
When does nondisjunction occur and what happens?
It occurs during meiosis when homologous chromosomes fail to separate and result in an abnormal amount of chromosomes.
Are dominant or recessive autosomal genetic disorders more common, why?
Recessive, because you can be a carrier and not get the disease.
What is a karyotype?
The number and visual appearance of chromosomes in a cell’s nuclei.
List three chromosome disorders and identify them as either monosomy or trisomy.
- Down syndrome- trisomy
- Turner’s syndrome- monosomy
- patau syndrome- trisomy
