Study GENETICS Flash Cards

 
Pile Management Card
GENETICS

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lethal allele
causes the death of an individual organism, often early in development, and so the organism does not appear in the progeny of a genetic cross
pleiotropy
1 gene affects numerous distinct and seemingly unrelated characteristics
expressivity
the degree to which a trait is expressed
complete penetrance
all in population show expected phenotype
incomplete penetrance
part of the population with genotype doesn't exhibit the phenotype
dominance is a result of...
interactions bw genes at the same locus, it doesn't alter how genes are inherited, classification of dominance depends on the level at which the phenotype is examined
Codominance
heterozygotes express phenotypes of both homozygotes
incomplete dominance
heterozygous phenotype is intermediate of both homozygous phenotypes "blending"
complete dominance
phenotype of the heteroYgote is the same as the phenotype of one of the homozygotes
Turner syndrome (XO)
form normal female genitalia, but lack ovaries
Mosaicism
when cells in one part of an organism differ genetically from those in another part
[male calicos-rare have Klinefelter's syndrome XXY or a chimera(fusion of 2 embryos)
Klinefelter's syndrome (XXY)
males with small testes, can develop breasts (infertile)
XX with SRY
genetically female, but appearance is male (infertile)
Androgen Insensitivity Syndrome
genetically male (XY) but don't respond to testerone until after puberty, appear female at birth, but may develop male structures following puberty (infertile)
Embryonic Development:Internal Structures
Mullerian duct lost in males
Wolffian duct lost in females
SRY
necessary for formation of male internal and external genitalia
AZF
necessary for sperm formation
PAR1,2
conserved in both X and Y chromosomes & is region where X and Y pair; where recombination can occur between X & Y
metamale
male, but weak and sterile. impaired development
intersex
has a mix of male and female characteristics
metafemale
female, but with developmental problems, may not complete development
genic balance system (X:A ration)
x chromosomes have genes causeing female characteristics, autosomes not the y chromosome have genes for male characteristics, ratio of X chromosomes to autosomes determines sex
environmental sex determination
chemical cues
temperature (some reptiles ex: turtles)
genic sex determination
no obvious sex chromosomes, genes for sex determination carried in other chromosomes, occurs in plants and protists
ZZ/ZW systems
birds, moths, some amphibians and Fish
XX/XO systems
grasshoppers
XX/XY systems
some plants, insects, reptiles, all mammals
T.H. Morgan & Sex linkage
-worked with flies (red eyes & white eyes)
Meiosis 2
replicated chromosomes move to separate cells final product: 4 cells; only 1 set of homologous chromosomes per gamete
Meiosis 1
homologous chromosomes move to separate cells with their replicates
Recombination/ "crossing over"
homologous chromosomes trade DNA
Mitosis
process by which the nucleus of a eukaryotic cell divides result: normal # of chromosomes per cell
homologous chromosomes
two chromosomes that are alike in structure and size and that carry genetic information for the same set of hereditary characteristics
Eukaryotic Chromosomes
Chromatin --> DNA --> have histone proteins
for a cell to reproduce:
1) replication (copy genetic material)
2)separate copied genetic info
3) cell division
Chi-Square equation
X^2 = sum (observed - expected)^2
______________________
expected
Steps for using chi-square test
1) propose hypothesis
2)calculate expected values and record observed values
3)apply chi-square formula
4)interpret calculated chi-square value
(a-calculate degrees of freedom, b-determine p value, c- interpret as significant or insignificant) pvalue less or equal to 0.05 is significant, d- state relevance to your hypothesis
The Chi-Square Test
commonly used statistical method to test hypotheses by evaluating goodness of fit
2nd binomial expansion equation
P = n! X p^xq^(n-x)
_________
x! (n-x)!
Binomial Expansion equation
(a + b)to the nth power

a= prob. of outcome 1
b =prob. of outcome 2
n = total # of events
binomial expansion can be used to determine.....
the probability that a certain proportion of the offspring will have a specific characteristic
Binomial Expansions
the probability that an unordered combination of events will occur
a testcross could be used to
determine whether a parent is heterzygous dominant or homozygous dominant
The product or multiplication rule
the probability that two or more independent events will all occur is equal to the product of the individual probabilities of the events
The Sum or Addition Rule
the probability that either two or more independent events will occur is equal to the sum of the individual probabilities of the events
random sampling error
deviation bw observed and expected outcomes due to chance - - - is higher with small sample sizes
Probability equation....
# of individuals with a given phenotype
___________________________
total # of individuals
Law of independent assortment
during gamete formation different pairs of alleles segregate independently of each other
dihybrid cross
a cross bw parents that are homozygous for different alleles at two loci (AABB x aabb) OR a cross bw parents that are both heterozygous for two traits (AaBb x AaBb)
sex chromosome
chromosomes that differ morphologically or in number in males and females
recessive
refers to an allele or phenotype that is expressed only when homozygous
locus
position on a chromosome where a specific gene is located
haploid (n)
possessing a single set of chromosomes
first filial
offspring of the initial parents
dominant
refers to an allele or phenotype that is expressed in homozygotes (AA) and in heterzygotes (Aa)
diploid (2n)
possessing two sets of chromosomes
codominance
type of allelic interaction in which the heterozygote simultaneously expresses traits of both homozygotes
autosome
chromosome that is the same in males and females; nonsex chromosome
allele
one of two or more alternate forms of a gene
Backcross
a hybrid (heterozygous) is crossed to its parent or a genetically similar individual to obtain a higher proportion of offspringwith genotypes similar to the parent
Testcross
cross to determine whether an individual with a dominant phenotype is homozygous or heterozygous. the Unknown is crossed to a homozygous recessive and progeny are analyzed (A_ x aa)
Monohybrid Cross 2
a cross bw parents that are homozygous for different alleles at 1 locus (AA x aa)
Monohybrid Cross
a cross between two parents that are both heterozygous at 1 locus (Aa x Aa)
heterozygous
possessing 2 different alleles at a locus
homozygous
possessing 2 of the same allele at a locus
genotype
genetic composition
phenotype
appearance
Mendel's Law of Segregation
two copies of a gene segregate(separate) form each other during transmission form parent to offspring
reasons Mendel succeeded when others failed?
studied populations instead of individuals, used a quantitative approach (physics training), patient(8 seasons), formulated hypotheses based on initial observations and tested, carefully chose the species used (garden pea): easy to cultivate, short generation time (1 season), many offspring, flower protected form foreign pollen, no reduction in fertility over generations, clearly distinguishable characters (2 varieties), used pure-breeding stock
Gregor Mendel
studied peas
how long are variable number tandem repeats?
each repeat is 10-60 nucleotides long
length polymorphisms
simple sequence repeats, variable number tandem repeats, copy number polymorphisms
Sequence polymorphisms
single nucleotide polymorphisms, restriction fragment length polymorphisms
DNA Polymorphisms
having more than one allele type for a gene or a DNA marker in non-coding DNA
types of DNA markers in genomic DNA
genes, allels, & loci
PCR machines
allow you to vary temperature of teh chemical reaction at timed intervals
PCR uses?
DNA polymerase that can function near boiling temperature, two primers that hybridize to each end of sequence to be amplified. dNTPs (nucleotides to make the new DNA strand), buffer (to stabilize the reaction), PCR machine
polymerase chain reaction needs
only a small amount of double-stranded DNA to start
PCR - polymerase chain reaction
Kary Mullis
Western Blot
proteins run on a gel and blotted. probe is usually an antibody. detects size of a specific protein or when the protein is expressed
Northern Blot
RNA on gel and membrane instead of DNA. Detects when specific RNA sequences are expressed
success of hybridization depends on
temperature
salt
sequence
concentration
hybridization
complementary strands of nucleic acids find each other and bind (A to T & G to C)
DNA Ladder
a 'ruler' to measure size of the DNA products
Gel Electrophoresis
1) DNA fragments separated by size in an electric field
2)DNA negatively charged: distance migrated is proportional to size of fragment
3)separated through gel matrix
What is used to separate DNA fragments?
Gel Electrophoresis
3 types of restriction enzymes
1) type 1: recognize specific sequence, but cut DNA at random sites distant from recognition site
2) type 2: recognize a specific site and cut DNA within the recognition sequence
3)type 3: recognize specific site and cut DNA about 25 bp from site
what does bacteria use to defend against nucleic acids from viruses?
restriction enzymes
what are used to cut DNA?
restriction enzymes
DNA amplification (polymerase chain reaction)
-need very little genomic DNA
-identifies small DNA fragments
-need to know more about DNA sequence
Nucleic Acid Hybridization (Southern Blot)
1)need more genomic DNA
2) can identify large DNA fragments
3) dont need to know DNA sequence
homozygous
same allele type in both chromosomes
heterosygous
different allele types
DNA contains?
-genes - repetitive DNA - pseudogenes - other noncoding regions
DNA is packaged in?
chromosomes
DNA -- DNA REPLICATION -- TRANSCRIPTION -- RNA -- TRANSLATION -- PROTEIN
EXCEPTIONS: DNA -- REVERSE TRANSCRIPTION -- RNA -- RNA REPLICATION -- PROTEIN
The Central Dogma
-Francis Crick
fundamental properties of DNA
1) DNA can carry large amounts of information by varying the sequence of nitrogenous bases
2)complementary nature of bases makes it possible to replicate DNA
3)the Central Dogma
Genetic Analysis (Beadle & tatum)(5 steps)
1) decide which process to study
2)decide what sort of mutations you expect if the process is disrupted
3)identify mutants by doing a mutant screen
4)perform complementation tests to find out how many genes you've identified
5) identify the gene products, what ehy do, how they interact with each other, and the order in which they function
operational definition of a gene
a set of mutations that make up a single complementation group
a minus sign in the complementation matrix.....
means that the indicated mutations do not complement one another
a plus sign in the complementation matrix....
means that the indicated mutations do complement one another
heterokaryon
forms when two Neurospora filaments merge, forming a new hybrid filament with multiple nuclei from each parent
analyzing ________ can help us determine the order________________
mutants; of events in a pathway
each _____ codes for one _______
gene; protein
this can be used to isolate a set of mutants affecting a single bilogical process.
mutant screen
the organisms response to protein defects depends on which __________
portion of the pathway is blocked
progression through biochemical pathways is controlled by ________.
proteins
analysis only tells ___of components, not _____of all. could have other intermediates.
order; identity
to determine the sequence of events ?? (3 steps)
1) develop a hypothesis
2)predicted the expected outcome if an enzyme was missing
3)determined whether the results corresponded to the original hypothesis
beadle & tatums goal??
to show the link between biochemistry and genetic analysis
mutant
result of a mutation
mutation
any heritable change in genetic material
Beadle & Tatum worked with
flies bc they were complex
"one gene, one protein"
George Beadle & Edward Tatum
genes regulate
specific chemical events
blocking different enzymes causes
different defects
gene defects are caused when?
produciton of the correct enzyme is disrupted and the pathway is blocked
a defect in "breakdown of Phenylalanine and Tyrosine"
-build up harmful metabolites, defects in myelin formation(mental retardation; nervous system damage)
each step in a metabolic pathway requires a different....
enzyme
Breakdown of Phenylalanine and Tyrosine
"black urine disease"
Sir Archibald Garrod Proposal
he proposed that human disorders could be caused by inherited deficiencies in proteins
Sir Archibald Garrod's idea?
idea was that there is a heritable molecular basis for traits that affect appearance, disease susceptibility, and behavior
damaged proteins...
can malfunction, altering the appearance or behavior of an organism
Enzymes
are biological catalysts that accelerate chemical reactions; enzymes are proteins
functions of proteins in the cell (6)
1)regulate import/export across cell membrane
2)structural support
3)produce energy
4)cell signaling
5)synthesize or break down molecules
6)cell motility
DNA primary structure is?
antiparallel strands
DNA...
nitrogenous bases, phosphate group, sugar, double-helix, complementary base pairing (Adenine --> Thymine Guanine --> cytosine)
Watson,Crick, & Franklin 1953
came up with nucleotide structure
RNA viruses do not use____they use____
DNA; RNA
3 scientists that proved dna was the genetic material
avery, macleod, and mccarty
Frederick Griffith
showed that genetic material can be transferred from dead bacteria to live bacteria
evidence that chromosomes are necessary for heredity...
chromosomes reside in the nucleus, they split during cell division, chromosome number is constant in a single species, but differs between species
male and female nuclei fuse during?
fertilization
microscopy began in...
the late 1800s
population genetics
how the genetic composition of groups of organisms changes over time and space
molecular genetics
the chemical nature of genes and how cells transfer and express genetic information
transmission genetics
how individuals inherit their genetic makeup and how genes are passed to the next generation
concentrations in genetics
transmission genetics, molecular genetics, and population genetics
genomics
study of all genes in an organism to understand their molecular organization, function, interaction, and evolutionary history
genes
inherited units transmitted from parents to offspring in reproduction
genetics
the study of heredity and variation
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