Module 10.1: Heredity Flashcards
What is a Genotype?
Your DNA resulting in your genetic makeup
Genotypes are a combination of what?
Alleles possessed of a specific gene
What is a phenotype?
Combination of observable characteristics or traits - what you look like
What are included in phenotypes?
Only genes that are expressed
_______ is directly inherited from parents. ________ is not, however is influenced by genotypes
- Genotypes and phenotypes
_______________ are variants of a particular gene due to changes in gene sequences
Alleles
For each gene there can how many different alleles?
Many
An ______ is one specific way a particular gene can be expressed
Allele
What are two basic characteristics of an allele are?
- Dominant
- Recessive
What does allele affect?
Affects the phenotype when present in one copy
How many alleles must be present for a recessive allele to show up
Must be present in 2 copies to be expressed
What is a punnet square?
Graphical representation of the possible genotypes two individuals can produce when combined
What is the punnet square based on?
Alleles from both parents
A punnet square is a map of what?
Statistical outcomes or risks of inheriting a disease or condition
What is a dominant and recessive expressive in the punnet square
- Dominant expressed as Big B
- Recessive expressed as little b
Humans have how many pairs of chromosomes? How many are sex chromosomes and how many are autonomies? 3
- 23 pairs
- 2 sex hormones
- 44 autosomes
What is meiosis?
Division of a cell that reduces the number of chromosomes to half
What is an example of meiosis?
Diploid»_space;> haploid
What does meiosis entail?
Two divisions of the genetic material
During meiosis if there is a production of four haploid cells, what assortment of genes and chromosomes does each carry?
New assortment of genes and chromosomes
What does this image represent?
Meiosis
What is the mode of inheritance depend on? 2
- On whether an allele is dominant or recessive
- Also whether the gene that determines that trait appears on a sex chromosome or an autosome
One person carries more than how many possible combinations of a chromosome? How?
More than 8 million
1. +8 million combination of his or her partner
2. = A potential variability of 70 trillion genetic unique individuals
What does homozygous mean?
An individual with 2 identical alleles for a gene
What is heterozygous?
An individual with 2 different alleles for a gene
__________disorders tend to be more severe and produce symptoms when?
- Recessive disorders
- Produce symptoms at a much earlier age
_________disorders are not as common because these people are what?
- Dominant disorders
- These people are too sick to reproduce, thus the allele vanishes from the population
Dominant disorders that do not present until adulthood remain in populations why?
These individuals can reproduce passing on the disorder
Is it possible for alleles be co-dominant? If yes what is an example?
Yes, such as in AB blood type
What is Tourette syndrome an example of?
Autosomal dominant, but has many different symptoms
What is cystic fibrosis an example of?
Autosomal recessive
What is Marfan syndrome an example of?
Autosomal dominant
What is Marfan syndrome? What are signs and symptoms? 5
- Connective tissue disorder caused by a defect in the gene that tells the body to make fibrillin
- Long limbs
- Pectus excavatum
- Aortic aneurysm +/- dissection
- Lens dislocation
What is uniparental disomy?
Two copies of an allele from one parent
What is an example of uniparental disomy? 2
- It was discovered when a girl expressed cycstic fibrosis even though her mother was the only carrier of the recessive allele.
- This child received both the genes from the Mother
A Male inherits which chromosome from his father and which from his mother?
- Y from father
- X from mother
Females inherit which chromosomes from each parent?
X chromosomes from each parent
Are X linked traits passed from father to son?
Never
Can a father pass a X chromosome to his male child?
No
What is an example of an X linked trait? Who are carriers?
- Hemophilia
- Daughters are carriers, because her fathers X chromosome would make that mutant allele
What is Klinefelter syndrome?
Males with an extra X chromosome passed on from mother
What are some signs and symptoms of Klinefelter syndrome? 3
- Underdeveloped sexually - rudimentary testes and prostate
- Long arms and legs, large hands and feet.
- No pubic or facial hair, may develop Brest tissue
How common is Klinefelter’s syndrome? 3
- Common
- 1 in 500 Male births.
- Most men do not know they have it until fertility becomes a problem
What is Jacobs syndrome?
Males with an extra Y chromosomes passed on from their father
What are some signs and symptoms of Jacob’s syndrome? How common is it? Who is affected? 3
- Aggressive behaviour
- Higher prevalence among inmates in jails however there are many men leading normal lives who are XYY
- 1 in 1000 male births
What may lead to variation of genes?
Exposure to viruses, drugs or radiation can cause these change to genes.
What is deletion?
Part of the chromosome is missing
What is duplication?
Extra genes
What is translocation?
Gene has moved to another chromosome
What is inversion?
Genes switched position on the chromosome arm
Wha is the most common live born chromosomal abnormality?
- Trisomy 21
- 1 in 800 births
______ is usually a random event and not inherited
T21
Most cases of T21 are due to what?
Maternal Nondisjunction
Nondisjunction occurs when? 2
- The chromosomes do not separate in meiosis
- Thus causing +1 or -1 chromosomes in gametes
What increases the incidence of Nondisjunction?
Maternal age
Some cases of T21 are due to what?
Genetic translocation- this can be inherited
If an individual has a _________ they may not show any signs - normal, health individual. This individual has an increased chance having children with what?
- Translocation
- Down syndrome
Do the two copies of the genes received from each parent have to be identical?
No
What does this image demonstrate?
Autosomal Dominant gene inheritance
What does this image demonstrate
Autosomal recessive gene inheritance
What does this image demonstrate?
X linked recessive gene inheritance
