Chapter 24 lecture 18 Flashcards
Discontinuous (Qualitative)
traits possess only a few phenotypes (e.g red or white)
Continuous (Quantitative)
characteristics vary along a scale of measurement with many overlapping phenotypes (e.g. hair or skin color)
GWAS (Genome Wide Association Study)
an examination of many common genetic variants in different individuals to see it any variant is associated (Co-segregates) with a trait
Polygenic inheritance
occurs when one characteristic is controlled by 2 or more genes. often the genes are large in quantity but small in effect
ex. of human polygenic inheritance = height, skin color, and weight
DNase I hypersensitivity
DNASe I hypersensitive site: more open chromatin configuration site, upstream of the transcription start site
Histone modification
- addition of methyl groups to the histone protein tails
- addition of acetyl groups to histone proteins
Chromatin remodeling complexes
reposition the nucleosomes, allowing transcription factors and RNA polymerase to bind to promotors and initiate transcription
Acetylation of Histones
- Typically loosens DNA to make more Accessible
permits some transcription factors to bind to DNA
Methylation of Histone
- tends to make gene inactive
histones are bound tigher
Transcriptional activator proteins
bind to sites on DNA and stimulate transcription
- most act by stimulating or stabilizing the assembly of the basal transcription apparatus
- mediator
- regulation of galactose metabolism through GAL4
What activates and controls transcription of galactose metabolism?
GAL4
1. no galactose? GAL80 blocks GAL4
2. Yes Galactose? GAL4 interacts with basal transcription apparatus and stimulates transcription
how? Galactose binds to GAL3 and changes conformation of GAL80
Transcriptional Repressors
bind to silencers!
Enhancer
DNA sequence stimulating transcription from a distance away from promotor
- nontraditional promotor
- Bends DNA to make it available for transcription
Insulator
DNA sequence that blocks or insulates the effect of enhancers
Most transcriptional activator proteins affect transcription by interacting with _____.
a. introns
b. the basal transcription apparatus
c. DNA polymerase
d. nucleosomes
b. the basal transcription apparatus
Metallothionein (MT)
family of cysteine-rich, low molecular proteins with the capacity to bind both physiological (zinc, copper, selenium) and xenophobic ( cadmium, mercury, arsenic, silver) heavy metals
Multiple Response Elements (MREs)
found in the upstream region of the metallothionein gene
- activator proteins bind to several MREs and stimulate transcription in response to heavy metals
What are some examples of response elements found in eukaryotic cells?
- heat-shock element (response to heat and other stress)
- GLucocorticoid response element ( responds to glucocorticoids)
- Phorbol ester response element (phorbal esters)
- serum response element (serum)
T/F Genes can be regulated by splicing?
True!
Alternative splicing - every category of cancer hallmarks
VEGF alternative spicing - regulates angiogenesis in tumor cells
What does RNA slicing lead to?
degradation of mRNA or to the inhibition of translation or transcription
RNA cleavage
RISC (RNA-induced silencing complex) containing an siRNA pair with mRNA molecules and cleavage to the mRNA
Transcriptional silencing
altering chromatin structure
In RNA silencing, siRNAs and miRNAs usually bind to which part of the mRNA molecules that they control?
a. 5’ UTR
b. the segment that encodes amino acids
c. 3’ poly (A) tail
d. 3’ UTR
d. 3’ UTR
mostly where small RNAs bind
way of controlling amount of message in a cell.
- has to confer some advantage because maintained throughout all eukaryotes
Quantitative Genetics
deals with phenotypes that vary continuously (in characters such as height or mass)
Relationship between genotype and phenotype quantitative continuous) characteristics
- exhibit complex relationship between genotype and phenotype
- are likely polygenic
- may have environmental influences
- phenotypic ranges may overlap
- cannot use standard methods to analyze
Meristic characteristics
type of quantitative characteristic (continuous)
- determined by multiple genetic and environmental factors, and can be measured in whole numbers
i. e. animal littler size
Threshold characteristics
type of quantitative characteristic (continuous)
- measured by presence or absence
susceptibility to disease
- only 2 possible phenotypes (trait is present: yes or no)
- when reach threshold value the trait is expressed
Polygenic inheritance
- refers to quantitative (continuous) characteristics controlled by cumulative effect of many genes
- each character still follows Mendel’s rules
- may be influenced by environmental factors
Population
group of individuals of interest
- all members of a particular group
sample
small collection of individuals from the population
- a subset of the population that should be representative of the larger population
frequency distribution
- graph that displays the number or proportion of different phenotypes
- phenotypic values are plotted on the horizontal axis, and the numbers (or proportions) of individuals in each class are plotted on the vertical axis
Normal distribution
bell shaped curve
skewed distribution
happens when more of 1 X gets inactivated
- the tail of one end is expressed more
Bimodal distribution
have a distribution but individuals may fall into more than 1 category
A geneticist is interested in whether asthma is caused by a mutation in DC112 gene. the geneticist collects DNA from 120 people with asthma and 100 healthy people and sequenced their DNA. She finds that 35 of the people with asthma have a mutation in the DS112 gene. What is the population in this study?
a. the 120 people with asthma
b. the 100 healthy people
c. the 35 people with a mutation in their gene
d. all people with asthma
d. All people with asthma
mean
the average of a set of values
- provide info about the center of a distribution
variance
the variability of a group of measurements
- provides info about variability of a group of phenotypes
- the greater the variance, the more spread out the distribution is about the mean
or how broad the tails are
standard deviation
the square root of the variance
- the proportions of a normal distribution occupied by plus or minus 1,2, and 3 standard deviations from the mean
1 = 66%, 2 95% 3 99%
the measurements of a distribution with a higher ____ will be more spread out.
a. mean
b. variance
c. standard deviation
d. both b and c - since the 2 are related
d. both b and c since the two are related
Correlation
when two characteristics are correlated, a change in one characteristic is likely to be associated with a change in the other
- does NOT demonstrate a cause-and-effect relation . it simply means that a change in a variable is associated with a proportional change in the other variable
correlation coefficient
a statistical measure of the strength of association
- describes the relation between two or more variables
- the stronger the correlation the bigger the number until you get to 1, which is perfect
Positive correlation
there is a direct association between variables
- they both increase
- strong positive is almost a straight line
weak positive is when there is a spread out cluster of points
Negative correlation
indicated that there is an inverse association between variables
- as one increases the other decreases
correlation of zero
there is no association between variable
regression
predicting the value of one variable, if the value of the other is given
ex. biomarkers (heart attack proteins if there then assumes to have had one)
regression coefficient
represents the slope of the regression line, indicating how much one value changes on average per increase in the value of another variable
regression line
defines the relation between two variable
- the line that best fits all the points on the graph
In lubbock, Texas rainfall and temperature exhibit a significant correlation of -0.7. which conclusion is correct?
a. there is usually more rainfall when the temperature is high.
b. there is usually more rainfall when the temperature is low
c. rainfall is equally likely when the temperature is high or low
b. there is usually more rainfall when the temperature is low
so as temp goes down rainfall goes up. so a negative correlation
heritability
the proportion of the total phenotypic variation that is due to genetic difference
briefly explain how the number of genes influencing a polygenic trait can be determined?
cross two individuals that are each homozygous for different genes affecting the traits and then intercross the resulting F1 progeny to produce F2. determine what proportion of the F2 progeny resembles one of the original homozygotes in the P generation. this proportion should be (1/4)^n wheren equals the number og loci with a segregating pair of alleles that affect the characteristics
phenotypic variance
due to genetic factors and how much is due to environmental factors
if the environmental variance (Ve) increases and all other variance components remain the same, what will the effect be?
a. broad- sense heritability will decrease
b. broad sense heritability will increase
c. narrow-sense heritability will increase
d. broad-sense heritability will increase, and narrow-sense heritability will increase
a. broad- sense heritability will decrease
