exam 2 BSC 2010 spielbauer Flashcards
inheritance
traits passed from parents to offspring
blending inheritance
theory that genes of a child are a mix of the the parents
particulate inheritance
there are specific genes (parts) that are passed down from each parent, not just a mix of them
gregor mendel
father of genetics, did pea plant experiements, discovered particulate inheritance
cross-fertilization
fertilizing one plant with another plant
self-fertilization
fertalizing a plant with itself
character
observable physical features
trait
forms of characters (wrinkled vs smooth seeds)
true-breeding variety
always same color flower when crossed, same traits as parents
reciprocal cross
each plant recieves and donates pollen between each other
monohybrid cross
true breeding purple x true breeding white -> f1 -> selfed -> f2
P Generation
The parent generation, the originals
F1 generation
the first filial (child) generation
F2 Generation
the children of the F1, second filial generation
Gene
discrete particulate factors
Locus
place where DNA is
Allele
diff versions of the same gene
Genotype
what their genes are, ex AA or aa
Phenotype
How that gene is expressed, ex wrinkled or smooth
Dominant vs Recessive Allelle
Dominant is expressed over recessive
Law of Segreation
Allelles are segregated equally in gametes
Genotypic ratio
how their alleles were in relation (1:2:1)
Phenotypic ratio
how their appearance was in relation (3:1)
Test Cross
plant dominant phenotype (A-) is crossed with homo recessive (aa)
- Explain the differences between blending inheritance and particulate inheritance. What evidence did Mendel’s monohybrid cross uncover that supported particulate inheritance and didn’t make sense with blending inheritance?
blending inheritance suggests that the genes mix together - in the monohybrid cross, it wouldn’t make sense that there are 3 purple flowers and one white, they would all be light purple. In the next generation, it wouldn’t make sense that that 2 purple flowers would result in a white flower.
- Describe the two ways that Mendel controlled the mating of pea plants (involved pollen transfer) so he could know which parents produced specific offspring.
cross fertilization, chose the specific plants that he would transfer pollen to, and then also did a self hybrid in which he put the pollen on the same plant.
- What was the goal of Mendel’s experiments? What was he trying to understand?
How genes were passed on, and explain phenonmenon that did not makes sense with the idea of blending inheritance
- Explain the process that Mendel went through to do his monohybrid cross. Explain how he created the Parental generation, and F1 generation, and the F2 generation. What were the phenotypic ratios of each generation?
parental gen was created by true breeding crosses, f1 resulted in monohybrids(all Aa), and then f2 resultd in the 3:1 phenotypic ration and 1:2:1 genotypic ratio
- What patterns did Mendel observe in all 7 of his monohybrid crosses? How did the phenotypes present change from generation to generation? What about the phenotypic ratio in the F2 generation?
3:1 phenotypic ratio in the f2 generation
- Explain what is meant by the underlying 1:2:1 “potential offspring” ratio that Mendel saw in the F2 generation of his pea plant crosses. How did he find this underlying ratio? Why could some of the purple flowers produce white offspring, while the other purple flowers could not?
Some could produce white offspring because they both had the recessive allelle, and they could create a flower that had both recessive allelles so they became white, found the potential ration in the f3 generation
- Be able to define and explain the relationship between the terms: genes, alleles, genotype, phenotype, dominant, recessive, homozygous, and heterozygous.
genes are made up of allelles. the genotype is the allelles that an organism has and the phenotype is how they are expressed. Dominant genes express over recessive genes, and a homozygous organism has 2 of the same allelle and a heterozygous organism has 2 different allelles.
- Explain the Law of Segregation. What does it mean? And how does it relate to Mendel’s experiments?
each gamete recieves only one copy of an allelle
- Following the Law of Segregation, what alleles will an individual with Aa genotype put into each gamete? What about AA genotype? Or aa?
Aa (A, a, A, a) AA (A,A,A,A) aa(a,a,a,a)
- What is a Punnett square? What does it allow us to visualize? What do you write on the sides of the square, and what do you write in the intersections in the middle?
helps to vizualize the genetic probability of offspring
- Describe how a test cross works. What do these allow you to do?
allows you to find the genotype of a unknown dominant plant - if thye have white offspring they are hetero
- Imagine you did a test cross between an individual with a dominant phenotype but unknown genotype (A_) and a homozygous recessive individual (aa). If you got a phenotypic ratio of 50% dominant and 50% recessive, what genotype must the dominant parent (A_) have? Making a Punnett square may help.
Aa, because there is no way for the recessive phenotype to appear with a AA for the parent.
multiplication rule
multiply independt events to find the prob that they will both happen
independent events
one does not influence the other, the probabilities are seperate
addition rule
add probs of mutally exclusive events to find the probability of either happening (or)
mutually exclusive events
dont have anything to do with the other
law of independent assortment
genes are seperate from each other and go into gametes seperately
dihybrid cross
pairs of traits to show tht they assort independently
pedigree
diagram that shows the inheritance pattern in a family
rare dominant allele
dominant, but rarely expressed (every affected individual has affected parent)
rare recessive allelle
heterosygotes can carry but many not be affected (2 heterosygotes can result in the affected offspring with a ratio of 3:1 affected)
- Explain why it is possible for a Rr x rr cross to produce offspring that are all rr.
because everything is just probability, each child has a 50% chance of being rr
- Why can we relate pennies to genotypes and flip outcomes to alleles? Think about the Law of Segregation.
This is because each allelle has an equal chance of being in the gamete, so it is all chance just like a coin flip
- Explain the basic rules of probability. What is the probability of a guaranteed event, an impossible event, or an event with multiple outcomes?
100%, 0%, < 100%
- What is the probability of you and another person independently flipping pennies and both landing on heads? What rule of probability are you applying here?
1/4, multiplication
- Explain the Law of Independent Assortment. What does it imply about the possible combinations of alleles when you are looking at the inheritance patterns of two genes? (If alleles of different genes can assort independently, will you always see the same combination of alleles? Or can there be any combination?
since they assort independently, and two genes can be in any combinations. They aren’t linked to each other. for example, green peas dont necearrisly have to be round or yellow peas don’t neceassrily have to be wrinkly, its all about the probabilyt of them happening together.
- Assume you found that the probability of producing yellow seeds in a monohybrid cross is 3/4, and the probability of producing wrinkled seeds from a different monohybrid cross is 1/4. If the alleles follow the Law of Independent Assortment, how would you calculate the probability of yellow and wrinkled seeds being produced in a dihybrid cross? (Remember the rules of probability)
3/4 x 1/4 = 3/16
- Describe how Mendel did his dihybrid cross. How did the process compare to his monohybrid cross?
he tracked two different traits instead of just one
- Assuming alleles follow the Law of Segregation and the Law of Independent Assortment, what possible alleles can be given by the genotype RRYY? What about rryy? Or RrYy?
RRYY(RY, RY, RY, RY) rryy (ry, ry, ry, ry) RrYy(RY, Ry, rY, ry)
- What is a pedigree? What do they show us, and how are they useful? How do they relate to Mendel’s laws of Segregation and Independent Assortment?
shows patterns of familial inhertiance, can show how traits are given and then expressed in each generation and how it is random
- Describe the patterns seen in the pedigree of a rare dominant allele.
every affect person has an affected parent
- Describe the patterns seen in the pedigree of a rare recessive allele.
often hidden until two heterosygous parents have a kid, and the kid displays the trait.
Chromosomal Theory of Inheritance
chromosomes follow mendels laws, and thats how/why they work
Sex-linkage
breaks law of segregation, genes may only be carreid on specific sex chromosomes
sex chromosomes
xx (female) xy(male)
gene-linkage
genes taht are close to each other on the same chromosomes are usually assorted into gametes together (breaks law of independent assortment)
sex-linked inheritance
traits associated with a particular sex
x-linked recessive
males are much more likely to have them, have affected maternal grandfathers and can only pass it to their daughters
thomas hunt morgan
demonstrated that traits could be carreid on sex chromosomes - mostly on eye color in fruit fliies
hemizygous
only one copy of some genes, males
wild type
the more common one in the wild
alfred sturtevant
morgan’s student, discovered crossing over
gene mapping
map the genes on the allelle using percentages, can predict whehter the genes are more likely to cross over or not
centrimorgans(cM)
measurement of gene mapping on an allelle
- How is the law of segregation seen in the segregation of alleles and homologous chromosomes into gametes?
each gamete gets one copu of each homologous chromosome
- How is the law of independent assortment seen in the segregation of alleles and homologous chromosomes into gametes?
chromosomes are assorted into gamete independently of one another
- How does sex-linkage break the law of segregation?
since genes are sometimes only carried on one chromosome, females can only give an x an and males can only give an y to a son
- How does gene-linkage break that law of independent assortment?
its not exactly completely random as genes taht are closer together on chromosome are usually assorted into gametes together
- What is sex-linkage, and what piece of evidence did it provide that helped support the chromosomal theory of inheritance?
when genes are on a sex chromosome, and it supported the idea that genes are on chromosmes
- What is gene-linkage, and what piece of evidence did it provide that helped support the chromosomal theory of inheritance?
when chromosomes cross over, they are likely to stay together if they are closer, meanign that the recombinant frequence is lower - doesnt always happen
- What is sex-linked inheritance? What are the common features of a rare recessive x-linked disorder? How does sex-linkage help explain these patterns?
affects son, affects his maternal grandfather, daughters are carriers
- Describe Thomas Hunt Morgan’s experiment that led to the discovery of sex-linkage.
flies, red eye father, white eye mother, white eye son, which shows how the mother can give x chromosome to the son, also how the father’s dominant red eyes did not give the son red eyes /
- Explain why males cannot give an X chromosome to their sons but can give one to their daughters.
because for the son they have to give a y chromosome
- Explain how gene mapping works. What can we infer about genes by comparing the percent of recombinant offspring in crosses like Morgan’s (AaBb x aabb)?
if the recombinant percentages are high, they are likley far way from each other on the chromosome, and if they are low, they are likely close together
- What does a smaller percentage of recombinant offspring imply about the relative location of two genes on a chromosome? (in an AaBb x aabb test cross)
they are probably close together
- What does a larger percentage of recombinant offspring imply about the relative location of two genes on a chromosome? (in an AaBb x aabb test cross)
farther away from each other
- What does having 50% recombinant offspring imply about the relative location of two genes? (in an AaBb x aabb test cross)
farthest apart from each other
- If you got a recombinant frequency of 15% between genes A and B, a recombinant frequency of 10% between A and C, and a recombinant frequency of 5% between genes B and C, which gene would be between the other two on the chromosome?
A C B
incomplete dominance
intermediate phenotype
codominance
2 allelles of a gene display both at the same time ( blood)
discrete traits
clear categories depending on the allelles (purple v white flowers)
quantitiative traits
vary within a range (height, weight, etc)
polygenic trait
character affected by multiple genes (wheat kernels have 3 diff geners taht contribute to color)
pleiotropy
one gene affects multiple characters (gene for a diseases affects other parts of the body
epistasis
one gene can influence anothers gene’s impact on a character
phenotypic plasticity
enviornment can influence a gene’s impact on a character
lethal allele
causes the death of an empbryo when homozygous
lateral gene transfer
transfer of genetic material between individuals
conjunction
transfer of DNA between prokaryotes
transformation
DNA from the enviornment into the prokaryote
transduction
tranfer from one p to another through a virus
plasmids
circular DNA molecule distinct from the chromosome in prokaryotic cells
sex pilus
initiates contact btw cels
conjugation tube
tube that allows info to pass from donor to recipient (not recprical)
antibiotics
kills bacteria
antibiotic resistance
bacteria that survives passes on its resistant genes so the bacteria contineus to survive
alexander fleming
discovered penicillin the first antibiotic
- Diploids can only carry two copies of a gene in their cells. How is it possible for a gene to have more than two alleles?
it has other alleles, each diploid jsut carries two
- Explain the difference between incomplete dominance and codominance. (This can be tricky. Remember that incomplete dominance is the dominant allele not being fully dominant over the recessive, compared to codominance is two dominant alleles not being able to block the phenotype of the other, so they are both present.) Refer to the examples from class to make sure you know the difference.
incomplete results in the blending of the two phenotypes (light purple eggplants), whereas codominance displays both phenotypes fully (blood)
- Compare/contrast discrete and quantitative traits.
discrete -> either or , purple or white quantitiative -> scale, height weight
- Compare/contrast a polygenic trait and pleiotropy.
polygenic -> multiple genes influence one character
pleiotropyy -> one gene affect multiple characters
- How can pleiotropy allow one gene to impact multiple characteristics?
cycstic fibrosis, causes a problem that shows up in multiple places in the body
- What is epistasis? Describe an example.
one gene influences the expresssion of the other -> labs, they have one gene that says whether they are black or brown and another that says whether the color is deposited or not (if not they are yellow)
- What is phenotypic plasticity? Describe an example.
organisms phenotypes are variable depending on the enviornemnt
- What are lethal alleles? Describe an example. How are lethal alleles able to be maintained in a population?
allelles that kill the animal as an embryo, maintained through heterosygous carries who dont express it but can pass it on
- Describe lateral gene transfer, and compare it to vertical gene transfer (from parents to offspring).
one prokaryote to the next, not through parents and offspring
- Name and describe the three ways that prokaryotes use lateral gene transfer.
conjunction - create a lol conjunction tube and send over DNA, transformation - incorporation of genetic materal from the enviornment, transduction, prokaryote to virus to another prokaryote
- Describe the steps involved in bacterial conjugation involving the transfer of plasmids.
plasmid transfered through conjugation tube as a single strand, and then the other strand is recreated in the donor and recipient
- Explain antibiotic resistance and how it can spread in a population of prokaryotes. Why is this a problem?
the living bacteria have the genes to resist the antibiotic and then they lateral gene transfer to the other ones the stay alive genes and then they grow back stronger
DNA binding dyes
developed in the early 1900s
flow cytometry
tracked the amoutn of DNA, - S, G2, and M had twice as much DNA compareds to G1
transformation experiment
found that bacteria could incorporate env DNA into their own
r strain
non-deadly strain, when present with heat killed s strain, can be deadly
s strain
deadly strain, when heat killed is non deadly
dna-degrading protein
when added, the mice did not die
hershey-chase experiment
bacteriophages (virus) inject either a protein or DNA into bacteria to replicate themselves- found they injected DNA
bacteriophages
virus taht injects DNA into bacteria to repliate the virus
32 p isotope
tags the DNA
35 S isotope
tags the protein
centrifuge
whirly thingy that seperates the viruses and the bacteria, bacterial cells on the bottom
pellet
the lower part - had viral DNA
supernatant
upper part, proteins and the virus
nitrogenous bases
purines ( adenine and guanine) pyramindes (thymine and cytosine (smaller)
adenine
purine, big, binds with T
guanine
purine big, bind with C
thymine
pyraminde (small), binds with A
cytosine
pyramidine (small), bind with G
purines
A+G
pyrimidines
T + C
erwin chargaff
discovered that there was an equal amount of purines to pyrimidines
rosalind franklin
created an image of the atoms in DNA
x-ray crystallography
xray source to a lead screan to aDNA sample that imprinted on a photographic plate
watson and crick
combined the knlowdge of DNA to determine the strucutre
antiparallel strands
found taht the strands must be the opposite of the other
complementary base pairing
A must go with T and C must go with G
semiconservatie replication hypothesis
each parental strand is a template for a new strand
conservative replication hypothesis
both strands act as a single tamplate and produce one fully daughter molecule
dispersiec replication hypothesis
parent is dispersed among 2 daughter molecules
meselson stahl experiment
found that DNA replication was semi conservative
15 n
dense DNA indicator
14 n
the medium, the default
DNA replication intiation
unwindig the double helix and synthesizing RNA primers
dna replication elongation
synthesizing new strands of DNA using each of the strands a a template
dna repliation termination
ends the synthesis of DNA
replication bubble
forms at the origin, creates a big bubble and lil forks pop up to start teh replication
replication fork
lil pieces that are ready to start the dna repliation, look more like combs tbh
DNA helicase
unzips ur genes
topoisomerase
untwists the DNA so it doesnt look like a twizzler
primase
creates short RNA strands that start the DNA
primers
lil RNA strands that start the DNA
dna polymerase
attaches to the primers and adds nucleotides to the 3’ end
5’ end
beginning
3’ end
end
leading strand
built continuously
lagging strand
built discontinuously
okazaki fragments
lil discontinous fragment
DNA ligase
joins the okazaki fragments together
end- replication problem
when the replication fork reaches the end of the chromosome, the leading strand is complete but the lagging strand has a lil piece cut off so the chromosome keeps getting shorter
telomeres
reptitice non-coding sequences at the ends of eukaryotic chromosomes to protect coding regions
telomerase
adds telomeres back on
- What was the circumstantial evidence that DNA is the molecule of inheritance? List and describe how each piece of evidence was discovered.
dna is present in the cell nucleus and in chromosomes, doubles during hte s phase of the cell cycle and there is twice as much in diploid cells vs haploid cells
- Describe the Transformation experiment, and how it provided strong evidence that DNA is the molecule of inheritance.
r strain and s strain, r strain is non deadly and the s train is deadly. when heat killed, the s strain is non deadly, but when added to the r strain it becomes deadly again. this is because there is DNA being communicated between the 2. Then when adding a dna degrading protein, it is non deadly again, meaning DNA is what is transferring genetic information
- Describe the Hershey-Chase experiment, and how it provided strong evidence that DNA is the molecule of inheritance.
bacteriophages are virsuses that inject something into bacteria to create more of themselves. In order to see what they injected, they radioactively tagged phosporous (to identify DNA) and sulfur (to identify proteins) and put them in a centrifuge. They knew the virus would be on the top and the bacteria would be on the bottom, so they wanted to see which tagged thing would be on teh top or bottom. dound phosphorous on the bottom, concluded they were injecting DNA
- List the chemical components that compose DNA. Compare/contrast purines and pyrimidines.
phosophate and deoxyribose backbone, nucleic acid bases, adenine and guanine are purines and cytosine and thymine are pyrimidines. purines are bigger
- Describe the discovery made by Erwin Chargaff regarding the ratios of the bases found in DNA. Think about why these ratios help in our understanding DNA structure and function.
the amount of A and G = the amount of C and T
- Describe the discovery made by Rosalind Franklin regarding the shape of DNA.
discoveredi t was a helical molecule
- Describe the discovery regarding the structure of DNA that Francis Crick and James Watson found that Rosalind Franklin also discovered.
found that it was a helix with antiparallell strands
- Given everything discovered regarding the makeup and shape of DNA, describe its structure. What aspect of its structure allows both strands to contain the same genetic information?
anti parallell strands with complementary base paring so taht it can contain information in both strands
- Describe the three DNA replication hypotheses.
semi conservative - each strand gets a complemantary strand to create 2 new strands
conservative - original dna creates an entirely new copy
dispersive - the new and old dna is dispersive and share parts
- Describe how the Meselson-Stahl experiment was performed and how it provided evidence for the semiconservative DNA replication hypothesis.
n15 isntead of n14, but put in a n14 medium, and then the dna replicated - > first time, created intermediate weight DNA and then the second time it was have heavy and half light
- List and briefly describe the three steps of DNA replication.
intiation - elongation - termination
- Describe the initiation of DNA replication. Explain the function of DNA helicase, topoisomerase, primase, and primers.
repliaction bubble forms, replication forks form, and helicase unzips the genes while topoisomersase makes sure they dont turn into a twizzler, primerase makes primers which are little RNA segments that start the DNA
- Describe the elongation of DNA during replication. Compare/contrast the elongation of the leading and lagging strands. Which one is composed of Okazaki fragments? What does that mean, and how are they combined into a single, continuous DNA strand? Explain this process and the components involved.
lagging is made up of okazaki fragments because its made up of lil pieces taht ligasse stitches together. leading strand is chillin and continues onward and completely finishes
- Describe the termination of DNA replication. Compare/contrast termination when replication forks meet, when the leading strand reaches the end of the chromosome, and when the lagging strand reaches the end. What problem occurs when the lagging strand reaches the end of the chromosome? Why is this an issue?
leading strand ends normally, whole thing is replicated, where as the lagging strand has a little bit cut offf, but its ok bc telomeres
- Describe the end-replication problem. How are we able to overcome this problem?
at the end of replication a bit of DNA is cut off
- Describe what a telomere is and how they work.
little bit at the end of the chromosome that doesnt mean anything
- Describe telomerase and how it functions.
creates new code for the telomere so taht they can keep getting cut off
somatic mutation
occur in somatic/body cells - can impact individual but do not impact offspring
germline mutation
occur in gametes and are passed to offspring and future generations
incorporation error rate
the probability that an incorrect base wll be inserted is about 1 in 100,000
nucleotide mismatch
when an incorrect base is input and it doesn’t match - quickly repaired
proofreading
when it recognizes a mismatch, backs up and then fixes itself
mismatch repair
protein complexes scan the DNA for wacky hydrogen bodning and removes/replaces the nucleotide
mismatch repair protein
protein complexes scan the DNA for wacky hydrogen bodning and removes/replaces the nucleotide
abnormal hydrogen bonds
when a purine x purine or pyrmadine x pyramidine happens by accident
base-pair substitutions
when they accidentally take the nucelotide out of the old strand instead of the new strang
point mutation
a single base is changed, inserted or deleted
tautomeric shift
a base temporarily forms its rare tautomer which can pair with a different base
tautomer
same chemical formula with a different arrangement
deanimation
loss of an amino acid group in cytosine, forming uracil which makes an incorrect base paring
uracil
base in RNA that pairs with A
spontaneous mutations
caused by polymerase errors or spontaeous chemical changes in bases
induced mutations
caused by matagens like chemcials or radition that damage DNA
mutagens
things that induce mutations likesmoking, diet, uv radition, and ionizing radition
excision repair
removes damaged nucelotides and replaces them with the right ones
direct repair
can be repaired directly instead of replaces, like how photolayse breaks the dimer bonds cause in thymine by uv radiation
thymine dimers
adjacent thymine link together bc of UV radition
photolayse
breaks the dimer bond
silent mutations
do not affect protein function
loss of function mutations
prevent gene transcription or produce non functional proteins
gain of function mutatuions
alters the protein function
conditional mutations
produce a protein that only function sunder certain env. conditions
tyrosinase
mutated pigment protein that only activates in areas that are lower than body temperature which makes colder extremities that color (liek a siamese cat)
chromosomal mutations
affect long DNA sequences
deleterious
cause harm or damage
chromosomal mutations
chromosomal rearrangemnets
- deletion, 2. duplicaiton, transloaction, inversion
deletion
a portion of a chromosome is lost and happens when the chromosom breaks in two location and regions with out a middle segemnt - could be fatal if you are missing genes
duplication
a portion of a chromosome is repeated, happens when homologous chromosolmes break at diff positions, one has a deleiton and one has
translocation
a portion of a chromosome is incorrectly located - when two homologous chromostomes creak and exchange segments
inversion
portion of the chromosome is flipped - chromosome breaks twice and rejoins but the segment is inverted
- What are mutations? And what are some of the general reasons they can occur?
when mistakes happen and change the DNA sequence
- Compare/contrast somatic and germline mutations. Which type can be passed on to future generations? Which type impacts only an individual?
germline impact future generations and somatic only effects the individual
- Explain how germline mutations help provide the raw material for evolution.
they can cause changes that may or may not be evolutionarliy useful, and if it is, then it continues to be in the population
- What is the incorporation error rate? And how is DNA polymerase able to correct itself?
around 1 in 100,000, and they proofread and mismatch repair if need be
- What happens if DNA polymerase causes a base pair mismatch and doesn’t catch its mistake?
becomes a point mutation
- What are the two ways that mismatch repair proteins can make a mistake? What are the results of each of these mistakes?
remove the nucleotide and replace it - can accidentally remove the wrong nucelotide
- Compare/contrast the two ways that bases themselves can be altered in a way that causes them to be paired with the incorrect base.
tautomeric shift - base forms its rare tautomer that causes it to pair wiht the wrong base vs deamination where it C looses an amino acid and accidentally becomes a uracil
- What is the difference between spontaneous and induced mutations?
spontaneous happes bc of lil errors by the polymerase or by the chemical changes, where as induced mutaions are caused by mutagens
- What is a mutagen? List examples of chemical and radiative mutagens.
smoking, diet, uv radition, nucelar bombs
- What are the two ways that damaged DNA can be repaired? How does each work?
excision repair - removed the damged nucleotides and replaces them
direct repair - directly repairs the nucelotide (thymine dimer example)
- How do mutations impact cells? List and describe the four types of mutations based on their impacts on the proteins that result. How does each of these impact the phenotype of an organism with these mutations?
silent - doesnt do anything
loss of function - nonfunctional proteins
gain of function - altered fucntion
- Explain how a kitten might have point coloration when that allele is not in the population’s gene pool. What type of mutation is this? (Somatic vs Germline, Spontaneous vs Induced, Silent vs loss of function vs gain of function vs conditional) Describe how the mutation that causes point coloration impacts the protein and phenotype.
somatic, spontaneous, conditional
- List and describe each form of chromosomal rearrangement (Deletion, Duplication, Translocation, and Inversion. What situations cause each to occur?
deletion - portion ofo chromosome is lot
duplication - portion is repeated (break at diff points)
translocation - incorrectly located (break and exchange segments
inversions - portion of a chromosome is flipped
- Which type of mutation is more likely to be deleterious (harmful): a point mutation or a chromosomal mutation? Why?
chromosomal because more stuff can get messed up
Mc1R gene
melanocortin 1 receptor protein on melanocytes
eumelanin
brown/black pigment
pheomelanin
red/blond pigment (mutant mc1r causes red hair)
archibald garrod
hypothesized that genes encode enzymes
alkaptonuria
black urine diesase, caused by accumulation of homogentistic acid with recessive inheritance pattern - the non functional enzyme for not being about to break down the acid was inherited genetically
homogentisic acid
acid that accumlates in urine in alkaptonuria
beadle and tatum
developed a method for studying mutations taht ‘knock out metabolic pathways
“knock out” mutation
mutation that stops the gene that encodes for arginine
polypeptide
part of a protien
hemoglobin
single protein made of 4 polypeptide chains
central dogma of molecular biology
info flows from DNa to RNA to polypeptide (protein)
messenger RNA
contains info to build polypeptides (gives instructions)
ribsomal RNa
builds the amino acid chain
transport RNA
brings the next amino acid to add to growing polypeptide (ikea example)
gene expression
involves the transcription and translation of mRNA
rNTPs
add nucelotides to RNA
dNTPs
add nucelotides to DNA
promoter
sequence of DNA that tells where to start transcription
ribose
used instead of deoxyribose
exon
coding regions that are translated into polypeptides
intron
removed from pre mRNA and exons are put together
hybridization experiments
denatured DNA will hybridize with homologous single stranded RNA or DNA
RNA splicing
removing introns and splicing intron
consensus sequences
short sequences between exons and introns
snRNPs
small nucelar ribonuceloprotein particles
spliceosome
composed of snRNPs and additional proteins
branch site
location on intron where 5’ end joins to form loop
5’ cap (G caps)
cap added ot the 5’ end, facilitates to the ribosome and prevents digestion by ribonucelases
Poly A tail
added to the 3’ end, helps RNA leave the nucleus and contributes to the dtability
Explain how genes are expressed to produce phenotypes. What do genes encode for?
How does that produce a phenotype? (Think about the red hair allele as an example.)
each gene encodes for a polypeptides which influences phenotypes - ex. a mutation in the gene for red hair (MCR1) can make it so that the polypeptides formed cause the hair to be red
Explain how Archibald Garrod’s research involving alkaptonuria led to his hypothesis
that genes encode proteins.
he studied the black pee (alkaptonuria) and realized that it was probably because a non -fucntional enxqyme that could not break down homogenisitic acid
Explain Beadle & Tatum’s experiment. How did they knock out the metabolic pathway for
the production of arginine? How did this support the idea that genes encode enzymes?
they made bread spores, moved them into tubes and put them in minimal medium, and the ones that didnt grow (the defectivce ones) were put in different tubes with one other nutrient, and they foudn arginine helped it grow, meaning hte enzyme that encoded for arginine was non functional
What were the two discoveries made that changed the “One gene–one enzyme”
hypothesis to the “One gene–one polypeptide” hypothesis?
genes can encode for proteins other an enxyme and some proteins are made of multiple polypeptides
Explain the central dogma of molecular biology. How is genetic information expressed?
Describe the flow of the information, how it is transformed, and what processes
transform it
dna to RNa ro polypeptide, DNA to RNA is transcription and RNA to plypeptide is translation
Describe the three main products of transcription and explain how they work together to
form polypeptides. What parts does each play in this process? Which one contains the
information being expressed?
mRNa, rRNA, tRNA - mRNA reads the instructions, rRna builds the chain, and tRNA supplies the bases/materials
Describe the overall process of gene expression with relation to the processes involved
and where these processes occur within a cell.
template DNA is transcribed into mRNA and it is processed and moves out of the cytosol (nucleus ) and then it is translated to a polypeptide
Compare/contrast transcription and DNA replication.
transcription is from DNA to RNA, where are replication is DNA to DNA, also RNA is single stranded
Explain what happens during each step of transcription: initiation, elongation, and
termination.
initiation - binds to promoter
elongation - one strange with a ribose backone
termination - recognizes termination sequence na dseperates the RNA from the DNA template
Why is it much more acceptable for mutations (misplaced nucleotides by RNA
polymerase) to occur during transcription when compared to DNA replication?
RNA sequences are short, errors arent passed on to offspring and many RNA have a short life span
In what ways is mRNA (Pre-mRNA) processed after transcription to create mature
mRNA that is ready for translation? What sequences are removed? What is added to
each end
introns are removed, 5’ cap is added and 3’ poly A tail is added
Explain the differences between introns and exons, and how hybridization experiments
discovered introns. Why did a loop form in the DNA during the hybridization of mature
mRNA, but not during the hybridization of Pre-mRNA?
introns leave, exons stay - they found out bc the mRNa ould hybridize with the denatured DNA and it wouldn’t connect with the introns which let to them creating lil loops
Describe the process of RNA splicing. Explain how each of the components (consensus
sequences, snRNPs, spliceosome, and the branch site) are involved in the process of
removing introns
snRNPs bind near consensus sequences, and then the splicesome removes the intron by cutting 5’ end of intron and attacing it to branch site and cutting 3’ end to research intron and then splices the two exons together
What are the 5′ cap (G cap) and Poly A tail? What are their functions for the mature
mRNA molecule?
5’ cap is the beginning, it facilitaties binding to the ribsome and prevents digestion by ribonucleases
the Poly A tail is at the end and ithelps the mRNA leave the nucleus and helps with stability
Codon
genetic information that is chunked into 3 letter sequences
Nirenberg and Matthaei
discovered the first codons through experiments involving synthetic mRNA
Poly-U
made a chain on U which is straight phenylalanine
Radioactive phenylalanine
what was used to measure the radioactivity of the poteins porduced using different lengths of poly u
sense codon
61 code for amino acids, makes sense and encodes a protein
nonsense codon (stop codon)
terminate translation
start codon
starts translation
degenerate genetic code
each amino acid had 2-6 codons
transgenic organism
genes can be inserted into another organism and function
synonymous mutations
dont alter the amino acid
missense mutation
change the amino acid sequence
nonsense stop mutation
produce a premature stop codon
loss-of-stop mutatuion
change a stop codon to a sense codon and then the polypeptide
frame-shift mutation
insertions or deletions of one or more bases (not multiples of 3) ususally ends with a loss of function
amino acid attachment site
tRNA binds to a specific amino acid
anticodon
nucleotide triplet that is complementaaryt to the mRNA codon for the attached amino acid
wobble
third base of a codon does not always need ot match the anticodon (wobble room)
ribosome
consists fo the large subunit and the small subunit
large subunit
3 RNA
binding sites - APE
small subunit
validates the match of mRNA codon to tRNA anticodon
a (amino acid) site
tRNA binds to codon of mRNA
P (polypeptide) site
tRNA adds amino acid to polypeptide chain
E (exit) site
tRNA waits here until released from ribosome
Initiation complex
forms when small subunit binds to mRNA and locates the start codon
Protein release factor
binds and breaks bodn between polypeptide chain and tRNA
polyribsome/polysome
strand of mRNA with its associated probsomes
signal sequences
tells proteins where to go
RER (rough endoplasmic reticulm
RER signal sequence stops translation until ribosome at RER
phosphorylation
addition of phosphate groups, chaning the shape (function)
glycosylation
addition of carbs to form glycoproteins, which have many important functions
proteolysis
cutting long polypeptides into smaller pieces that have thier own function or removal of signal sequences
How does genetic information contained in mRNA encode for specific amino acids?
mRNA has codons which are then translated into polypeptides by going through the rough ER
Why do codons exist, and how were they discovered?
codons exist to code form specific amino acids, and were discovered by nirenberg and mathaei with the poly U experiemnt with synthetic mRNA
What patterns do you see when you look at the table of all amino acids? Can multiple
codons encode from one amino acid? Can one codon encode multiple amino acids? What can you infer about the code based onthese answers?
multiple codons can encode for one amino acid, but a codon cannot encode for multiple amino acids
Describe what is meant by the genetic code being degenerate.
many codons can code for a singe amino acid
Compare/contrast start and stop codons
start codon is an actual amino acid, where as the stop codon is nonsense
Compare/contrast sense/missense (stop) codons.
sense - codes an amino acid, missense/nonsense, do not code for an amino acid
What does it mean that the genetic code is universal? What are the implications of this?
all organisms use the same codons to encode the same amino acids - shows that genetic code is ancient and that genes from one organism can be inserted into another and still function.
Describe what is meant by a transgenic organism.
genes from one organism can be inserted inota nother and function
Explain how each type of mutation impacts the chain of amino acids produced:
synonymous, missense, nonsense (stop), loss-of-stop, and frame-shift
synonymous - literally does nothing bc they mean the same thing
missense - changes it to another amino acid, concerning especially if its methionine
nonsense - prematurely stops the process
loss -of-stop - keeps on going by accident
frame-shift - insertion or deletion of not 3 codons, which causes all the amino acids to be off
What are the two major sites on a tRNA molecule, and what is the function of each?
amino acid site (binds to a specific amino acid) and anticodon (nucleotide triplet complemtary to the mRNA codon for the attached amino acid
Explain the concept of “wobble” in reference to codons. What does this allow
wobble means that the third base of a codon does not always needd ot match the anticodon, which allows fewer tRNA variants while avoiding ambiguity.
Describe all of the major parts of a ribosome: large subunit, small subunit, A site, P site,
and E site
large subunit has the 3 tRNA binding sites, APE, and a small subunit which validates the match of the mRNA codon to tRNA anticodon. A is where the tRNA binds to the codon of the mRNA, P is where tRNA adds the amino acid to polypeptie chain and E is where the tRNA waits until its released from the ribosome
Explain the process of translation in detail. What happens during initiation, elongation,
and termination? What site do tRNA molecules bind to? What is the site where the
growing polypeptide chain is attached? Explain how termination works in translation
mu
Why is it beneficial that multiple ribosomes can translate a single mRNA molecule
simultaneously?
much more efficient than doing it one at a time
What helps direct polypeptides to different locations in the cell post/during translation?
signal sewuences
Describe the three ways that polypeptides can be modified post-translationally. How do
each change the polypeptide, and why might each be necessary
phosophorylation
glycolization
proteolysis
Gene regulation
allows genetically identical cells to have different phenotypes
sonic the hedgehog gene
produces a protein that regulated the epression of genes involved in development throughout the body
hox genes
set of genes encoding for regulatory proteins involved in specifying bodysegment identity
inducible genes
not expressed unless products are needed
repressible genes
usually expressed unless products are not needed
constitutive genes
expressed at a constant rate
transcription factors
reguatory proteins that control gene activity
repressors
prevent transcription
activators
stimulate transcription
lac operon
inducible sries of genes that create products that break down lactose
lactose
milk sugure
trp operon
repressible series of genes taht create prodcutss used to synthesize tryptophan
tryptophan
happy chocolate chmiecal
operon
series of genes with a single promoter
promoter
regulatory sequence
operator
regulatory sequence between the promoter and the geense, acts as a binding site for a repressor
negative regulation
repressor blocks the RNA polymerase, preventing transcription
positive regulation
activators stimulate the transcription of an operon, which is positive regulation
DNA binding site
where transcription factors bind to target DNA
allosteric site
where other molecules can bind
allolactose
inducer, binds ot the repressor where lactose is present
inducer
induces the expression of the gene by binding to the repressor
co-repressor
binds with the repressor to prevent gene expression
TATA box
TFIID
binds to the TAT box of the promoter
general transcription facots
basal transcription apparatus
multiple general transcriptuon facots bind, which forms the basal transcription apparatus
specific transcription factors
activators
enhancer
silencer
cell differentiation
epigenetics
chemcial modification of DNA “packaging” that influence gene expression
nucleosome
composed of 8 histone proteins around which DNA is wound
histone
things that dna is wound around
histone ‘tails’
htey have amino acid tails, therei s a strong attraction between positive histone tails and negative phosphate groups of SNA
acetlyation
addition of acetyl gorups to the end of histone tails, neutralizing thier charges and opening up condesnsed DNA
histone acetyltransferases
add acetyl grouds, allowing transcription
histone deacetylases
remove acetyl groups, repressing transcription
methylation
adding methyl groups to cytosine bases in DNa whic represses transcription
DNA methyltranderase
catalyzes modification f cytosines into 5-methylcytosine
Demethylase
catalyzing removal of methyl groups from cytosien
5-methylcytosine
binds to proteins involved in repression of transcription
CpG islands
regions rich in C and G which stop transcription if methylated
Hemimethylated
half is methylated bc of semiconsverative replication
Euchromatin
diffuse and light-staining; unmethylated (genes can be expressed)
Heterochromatin
condensed, dark-staining, methylated (genes are silenced)
Barr Body
either X in female mammals can be methylated/silences
monozygotic (identitcal) twins
3 yo identical twisn have nearly identical methylation patters, but 60 yo twins hte pattern may be very different
alternative splicing
differnt combos of exons are spliced toether to create differnt mRNas
MicroRNAs (miRNAs)
bind to mRNA to block translation or cause premature degradation
translational repressors
proteins bind to mRNas to prevent translation
ubiquitin
protein that identitfies other proteins for breakdown by the proteasome
proteasome
cell division
one mother cell gives rise to two daughter cells
reproduction
organisms pass genetic infor to offsprint through cell division
growth
increasing number of cells in eukaryotes
regeneration
regrowth of cells/tissues in eukaryotes
asexual reproduction
directly produces offspring that are clones. of the parent organism
sexual reproduction
produces gametes that are then fused together through fertilization to produce offspring with genetic variation
binary fission
prokaryotes
mitosis
eukaryotes, both unicelluar(like yeast) and multicellular (aspen trees)
mutations
only way asexual reproduction produces genetic variation
meiosis
eukaryotes only! 2 rounds of cell division to produce gametes
fertilization
fusion of two gametes produced via meiosis
gametes
sex cells with half the amount of chromosomes
haploid
gamete, half the chromosomes
diploid
somatic cell, all the chromosomes
zygote
product of fertilization
cell division signals
initiate cell divison
DNA replications
creates. acopy of cell’s genetic info
DNA segregation
distributes copies of DNA into two new cells
cytokinesis
divison of cytoplasm to form two new cells
ori (origin) site
start of the dna in a prokaryote (because. itis circular)
nuclear envelope
membrane around hte nucleus that protects DNA
centrosomes
chillinuntil mitosis or meiosis when it has to create spindles. topull apart chromatids
chromosomes
condense and hold genetic material
cell cycle
has two phases, interphase and m phase
interphase
G1 phase, S phase (DNA syntheis, DNA is replicated) , G2 phase
M phase
mitosis and cytokinesis
g1 phase
gap 1, cells carry out normal functions
g0 phase
resting phase outside of the cell cycle
S phase
DNA is replicated
g2 phase
cell prepares for mitosis, DNA is checked for errors
prophase
condensation of chromosomes, spindle assembly begins, chromin coils and creates chromosomes, kinetochores form at the centromere and centrosomes move toward poles. andproduce long protein fibers called microtubiles which form a spindle
prometaphase
nuclear envelope breaks down, chromosomes attach to the spindle
metaphase
alignment of chromosomes along the equatorial plane
anaphase
seperation of chromatids; migration to poles
telophase
chromosomes decondense; nuclear envelope re-forms
chromatin
uncondensed chromatid
kinetochore
centromeres
attach the chromatids together
sister chromatids
2 of the same chromatids
microtubule
long protein fibers that create the spindle
spindle
made of microtubules and move the chromatids to the pole
equatorial metaphase plate
line down the middle of the cell
contractile ring
ring made of actin to sinch and seperate the cells
actin
structual protein in the cell
cell plate
in plants, used to sepereate the cytoplasm
- What processes is cell division necessary for? And what do they each do?
reproduction (create new organisms), growth (add more cells to a multlicelluar organism and regeneration (re grow damaged tissues and cells)
- How do asexual and sexual reproduction differ? Describe each process.
asexual - only one organism, and its genetically identitcal, sexual - 2 organisms gametes fuse together
- Describe the two forms of cell division that are used in asexual reproduction. Which groups of organisms use each?
binary fission - prokaryotes, mitosis - eukaryotes
- Describe the general series of events that occur during cell division.
the dna is condensed into chromatin, and condenses further into chromatids. centrosomes form a spindle fiber made of microtubules, and then the nuclear envelope disintegrtes. The chromosomes line up on the equatorial plate and then the spindes attach tot them and pull them apart so they break in hald. Then, the cleavage is forme dna the contractile ring splits the two cells, and. thenucelar envelope re forms
- Describe the process of binary fission. Which organisms use this process?
prokaryotes
- Describe what happens to the: cell membrane, nuclear envelope, centrosomes, and chromosomes during cell division
- List and describe the phases and sub-phases of the eukaryotic cell cycle.
Interphase ((g0)G1, S, G2) and M phase (PPMAT)
- Describe the important things that happen during interphase and mitosis (general).
s phase - DNa is replicatied , g1 and g2 ar e prepatory phses, and in M phase the cells are replicated
homologous chromosomes
a pair of homologous chromosomes, one inherited from each parent
replicated chromosomes
after S phase, chromosomes have 2 identitical copies of one chromosome, each called sister chromatids, (whem counting chromosomes, count centromeres)
tetrads
homolougours chromosomes pair to form tetrads ‘’,,’’,,
crossing over
when chromosomes cross over and produce genentic diversity
chiasmata
points of crossing over
genetic recombination
rearragnement of DNa sequences by breaking and rejoing chromosome segments
reduction division
four genetically distinct haploud (n) cells called gametes chromosome number ishald
aneuploidy
an abnormal number of chromosomes in a cell
nondisjunction
chromosome pair fials to seperate at anaphase
monosomic
missing a chromosome
trisomic
extra chromosomsme
trisomy 21
down syndrome
karyotype
chromsome map
polyploidy
organisms with triploid, tetraploid, or even high er numberes ( failure of the spindle to form, failure of cytokinesis, polyspermy)
triploid
3n
tetraploid
4n
polyspermy
more than one sperm fertilizes the egg
cell cycle checkpoints
g1 checkpoint, s checkpoint, g2 checkpoint, and M checkpoint
cyclin dependent kinases (CDKs)
activated by binding to cyclin, phosphorylate proteins that reulare thes checkpoints
Cyclin
synthesized when the cell recives signals that it can pass through that checkpoint
retinoblastoma protein
blocks cell cycle progression until phsophorylated
necrosis
cell is damaged or starved for oxygen or nutrients - bursts, and when an organism dies, all of its cells die via necrosis
apoptosis
genetically programmed cell death, used when cell is malfunctioning, infected, or no longer needed
Hayflick limit
number of times a cell can divide
stem cells
lacks a hayflick limit, can develop into many differnte speciallized cells
cancer cells
malignant cells taht divide without restraint
- Explain how meiosis and fertilization both work together to create genetically diverse offspring.
crossing over, gametes merging, very diverse organism
- Compare/contrast mitosis and meiosis. What happens during each form of cell division? What are the products of each? What are the overall similarities and differences?
meiosis essentially has double and then when they get to the II versions its basiclaly mitosis
- Describe the parts and genetic makeup of a single unreplicated chromosome in contrast to a homologous pair of replicated chromosomes. How many chromosomes and chromatids are present in each?
- Describe the process of crossing over, and explain how it leads to genetic diversity in the gametes that are produced by meiosis.
- Explain how the stages of mitosis, meiosis I, and meiosis II differ.
- Describe how meiosis results in a reduction division
- Describe how the chromosomal makeup of a parent cell differs from the four daughter cells produced through meiosis. Also, how do the daughter cells compare to each other?
- Explain how nondisjunction results in aneuploidy. Explain the process and the results of this error in cell division.
- Compare/contrast nondisjunction in anaphase of mitosis, anaphase I of meiosis, and anaphase II of meiosis.
- Describe the resulting karyotype of a trisomic individual compared to a monosomic individual. Explain what type of gametes were fused to produce each.
- Describe polyploidy and explain the types of errors in cell division and fertilization that can result in polyploidy.
- Describe polyploidy and explain the types of errors in cell division and fertilization that can result in polyploidy.
- Which groups of organisms are more commonly polyploid, and which are not?
- Describe why the cell cycle must be regulated in unicellular organisms and contrast that with multicellular organisms.
- Describe what the cell cycle checkpoints are generally regulating (may want to read the text bubbles on slide 27 for more specific info).
- Explain the process of eukaryotic cell cycle regulation via CDKs, cyclins, and checkpoint proteins.
- Compare/contrast necrosis and apoptosis. Think about the situations when each would occur.
- Describe the Hayflick limit. Why is this beneficial?
- What type of cells lack a Hayflick limit? Why might this be beneficial or harmful?
- Describe the various mutations that impact cell cycle regulation that can result in unregulated cell division (which could lead to cancer).
