Beyond Mendelian Flashcards
Beyond Mendelian
- Genetic Linkage
- Semidominent/ co dominant alleles
- Enviromental effect (conditional alleles)
- Variation in chromosomes bumper ( polyploidy and aneuplouidy
What is genetic linkage?
- Genetic linkage mease that some genes are stuck together because they are close on the same chromosome
- Example, two beads on a string right next to eachother
What are semidominent and co dominent alleles?
- Semi dominant: incomplete, no allele is more dominant than the other. They mix
Co Dominent: both alleles expressed at the same time without blending
Ex;
semi mixes together like paint
co dom shows up side by side without mixing.
What are conditional alleles
- alleles that show their effects under certain conditions
- specific environment, temp sensitive alleles.
What is a polyploidy?
- when an organism has an extra set of chromosomes. instead of the usual 2
What are some plants that are polyploids?
- Wheat
- Strawberries
- Bananas
What is an anuploidy?
- How does this happen?
- When a cell has too many or too few chromosomes instead of the normal number
- This happens when there is non disjunction
What are some examples of aneuploidiy?
- Trisomy 21 ( extra chromosome) 3 copies of chromosome 21 instead of 2. ( down syndrome)
- Monosomy ( missing a chromosome) when a female only has one x chromosome instead of two
What are homologous chromosomes
Who are they from?
- Pairs of chromes.
- One from mama and the other one is from dada
What is gene linkage
- happens when 2 genes are on the same chromosome and get inherited together
- since they are close togheth they get passed down together.
What is crossing over?
When does it happen? ( which cell division process?)
What is the result of this?
- happens during prophase1 one of meosisi
- homo chromes, pair up and exchange segments of DNA
- Results in genetic diversity
If genes are far apart can they cross over, what about if the genes are close together?
- if they are far apart, they are more likely to cross over
- If the genes are close together, they are LESS likely to cross over.
What is the key point of gene linkage and crossing over?
- Genes are less likely to cross over if they are linked closely together
What are co-dominant alleles?
- Are they both expressed?
- Do the traits show up clearly?
- What is an example?
- Co-dominant alleles are both expressed, and both traits show up clearly.
Ex; Blood type AB, both A and B alleles are expressed to the person has A AND B proteins
What’s the deal with dominant versus recessive mutations?
Dominant: These are the stronger alleles that can hide the recessive trait
Functional versus nonfunctional alleles?
- What makes a protein work, and what doesn’t?
- Which one is dominant versus recessive?
- A functional allele makes a protein work ( dominant)
- A non-functional allele doesn’t make a protein work. ( recessive )
What is the key point on dominance?
- Dominant alleles produce activity( working protein) that can be seen by the organism while the recessive alleles don’t LACKS activity and only is shown when both alleles are reccessive.
A1 Vs A2 casein in milk.
- What does each one have at position 67
A1: Has histidine at position 67 ( think of histamine allergy)
A2: has proline at position 67 ( think of going pro in the league?)
Which cows make which Casein?
- Holstein cows, the black and white cows make both
- Jersey cows ( brown and black) only make A2
What is Sickle Cell disease?
- Sickle cell disease affects hemoglobin, the protein in red blood cells that carries oxygen.
- A mutation causes one amino acid in hemo which results in a sickles chape cell instead of round
Why is sickle cell a problem
- Sickle cells clump together when they ae not carrying oxygen
- Causes pain, organ damage and block blood flow.
What is the heterozygous advantage of sickle cell in relation to malaria
- If you have a normal hemoglobin gene and then a sickled one ( r), you don’t have a severe sickle cell disease
- You are more resistant to malaria, which is why the trait is more common in Africa, India, middle east, etc.
What is the risk with D1 athletes if they have the heterozygous trait for malaria?
Why?
- 37x higher risk of sudden death during intense exercise.
- Extreme physical activity reduces oxygen levels which can trigger sickling in cells
what are some enviroments that affect traits? ( external and internal)?
External: weather, temp, light and air quality
Internal: gene interactions, cell signals, metabolism
What are some examples of environmental effects on triats?
- Mendels experiment and test crosses
- Chlorophyll degredation
- 80 acres farm
How does mendels experiment and cross-testing relative to environmental effects on traits?
- environment can influence how genes are expressed even if the code is the same
How does chlorophyll degradation relate to environmental effects?
- Leaves change color
- Chlorophyll breaks down due to temp and light changes.
how does the 80-acre farm relate to environmental effects ( vertical famrimng and light manipulation
- vertical farming: instead of growing in feilds they are grown stacked in doors
- Ligh manipulation: changing wavelengths of light to control color and growth
What are the gene environment interactions in asthma?
- asthma is influenced by both genes and the environment
- genetic risks
Environmental triggers - Gene environment interaction
What are some risk factors for asthma?
- Early exposure to microbes
- Respiratory infections
- Allergens
- Low socioeconomic status
- Stress
- Obesity
- Occupational exposures
- Traffic-related air pollution
What is the common garden experiment?
Plants and animals are raised in the same environment to determine whether differences are due to genes or environment.
What are growth chambers ( what do they affect)
- Scientists control temperature, light, and humidity to see how different conditions affect development.
What is the key takeaway about environment and genes
- it’s not only genes; the environment plays a major role in how traits develop.
Dizygotic vs mono twins
- Di twins come from two different eggs and 2 different sperm, grow in same womb
- Mono twins come from one egg and one sperm
What effect does polyploidy have on plants?
- Makes them bigger and makes better crops.
Ex: Tetra grapes are larger than di grapes - Seedless watermelons tri pod bc chromes didn’t pair properly during meiosis
Why is anuploidy more common in older mothers
- the chromosomese dont as tighlty with age.
what does aneuploid result in with early human embryos?
- miscarriage.
Key takeaways with polyploidy and aneuploidy
- Polyploidy is useful because it makes bigger plants and seedless varieties
- Aneuplody happens due to chromosome missegregation and is linked to genetic disorders
- Cancer cells have abnormal numbers due to polyploidy or aneuploidy.
