Chapters 10-16 Flashcards
Is mitosis continuous?
yes
What is mitosis?
the division of 1 nucleus into 2 nuclei
What are the four phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
What happens during prophase?
chromosomes appear and condense
membrane around the nucleus disappears
microtubulars appears
What happens during metaphase?
Chromosomes are lined up in center of the cell
They get attached to microtubules
What happens during anaphase?
Sister chromatids separate by microtubulars
What happens during telophase?
Chromosomes begin to disappear
nuclear membrae appears
What is Cytokinesis?
The division of one cell into 2
How does cytokinesis work in plant cells?
A cell plate is placed in the middle of the cell to divide it
How is a cell plate formed?
vesicles are positioned by microtubulars and slowly become a solid mass
How does cytokinesis work in animals?
Actin filaments pinch the cell in at the middle until it splits.
WHat are the 3 check points in the cell cycle?
G1/S checkpoint
G2/M checkpoint
Spindle Checkpoint
What is checked at the G1/S checkpoint
Checks the size and that the cell has enough nutrients
What is checked at the G2/M checkpoint?
Is the DNA ok?
Is the replication complete
What happens if there is a problem at G2/M checkpoint?
DNA tries to get repaired. If not then the cell commits suicide AKA apotosis
What is checked at teh spindle checkpoint?
Are the microtubulars attached correctly?
Are the chromosomes in proper position?
What two proteins complete cell control on a molecular basis?
Cyclin Dependent Protein Kinases (CDK)
Cyclins
How do most organisms reproduce?
sexually
What two steps do organisms who reproduce sexually alternate between?
Meiosis and syngany
What is meiosis?
a reduction division in chromosome number
What is syngany?
fertilization. Fusion of 2 gametes, thus doubling chromosome number
Who first observed how sexual reproduction?
Van Beneden
What does diploid mean?
two copies of chromosomes
What does haploid mean?
one copy of chromosomes
What is a 2n cell called?
a zygote
What are the three life cycles?
Diploid life cycle, haploid life cycle, Alternative of Generation life cycle
What species goes through the diploid life cycle?
animals
What is the diploid life cycle?
2n organism -> gametes/n (meiosis happens) -> gamete + gamete -> 2n zygote (fertilization) -> zygote grows through mitosis into 2n organism
What species goes through the haploid life cycle?
Fungi and many algae
What is the haploid life cycle?
n organism -> gametes/n (mitosis is used) -> gamete + gamete = 2n zygote (fertilization) -> 2n = 4n spores (meiosis) -> n spores grow back to n organism (mitosis)
What does a gamete need in order to grow?
another gamete
What does a spore need to grow?
nothing, it can and does on its own
What species goes through the Alternative of Generation life cycle?
all plants and some algae
What are the two generations in the alternative generation life cycle?
Gametophyte and sporophyte
What is the gametophyte generation work?
n organisms -> n gametes (mitosis -> gamete + gamete = 2n zygote (fertilization) -> grows via mitosis -> makes a 2n organism -> n spores (meiosis) -> grows to n organisms
How does the sporophyte generation work?
Makes spores
What are the 8 stages in meiosis?
prophase 1, metaphase 1, anaphase 1, telophase1, prophase 2, metaphase 2, anaphase 2 telophase 2
What happens in prophase 1?
chromosomes appear (condense) Homologous chromosomes pair with each other
What is a tetrad?
a pair of homologous chromosomes
When does crossing over happen?
prophase 1
What is crossing over?
certain DNA is crossed over and breaks off and exchanges
What happens in metaphase 1?
homologous pairs line up
What happens in anaphase 1?
homologous chromosomes separate
What happens in telophase 1?
2n cells are created
What happens in prophase 2?
chromosomes appear
What happens in anaphase 2?
sister chromatids separate
What happens in telophase 2?
4n cells are created
What are the differences of mitosis and meiosis?
Mitosis has: 2 cells 1 division 2n resulting chromosome number Meiosis has: 4 cells 2 divison paring of homologous chromosomes tetrads crossing over and the resulting chromosome number is n
What are the differences between asexual and sexual reproduction?
Asexual- no variability produced, often a back up when sexual reproduction fails, some do this and sexual reproduction.
Sexual- variability, more expensive and more chances of failing, most organisms.
Who is Gregor Mendel?
Father of all genetics, Austrian monk, 1822-1844, studied math and science,
What did Mendel do his research on?
Peas
Why was Mendel successful?
Brilliant, trained in math, trained in scientific method, chose pea plants.
Why did Mendel choose pea plants?
Had a short generation, small, they could cross pollinate + sell pollinate
What does F1 generation mean?
Filial generation (or offspring)
What is a gene?
Holds information to make protein, made of DNA, helps control a particular trait, found at a particular location on the chromosome
What is an allele?
Alternative form of a gene
What is Locus?
Position of a gene on a chromosome
What is the allele for a homozygous Dominate?
RR
What are the alleles for a heterozygous?
Rr
What are the alleles for a homozygous recessive?
rr
What is a genotype?
Genetic information of a human
What is a phenotype?
physical appearance of organisms
What is a monohybrid cross?
When you watch one trait through generations
What is a dihybrid cross?
When you watch multiple traits at a time in generations
What is Mendel’s second law (law of independent assortment)
pairs of factors separate independently of each other
What are some examples where Mendel’s laws are not observed?
Incomplete dominance Environmental affect Pleiotropy Epistases Continuous variation Codominant alleles DNA in chloroplast in mitochondria
What is incomplete dominance?
When the heterozygote is intermediate between the homozygote
EX- in some flowers the colors get mixed
What is pleiotropy?
One allele has more than on effect on phenotype
What is Epistasis?
When one combination of genes has a dominant effect over other combinations that is a nonallelic gene
What is continuous variation?
Many genes affect a trait
What are codominant alleles?
more than one allele that is dominant
EX ABO blood types
What is a karyotype?
visual array of what your chromosomes look like
How do errors in chromosome numbers happen?
happens because of errors in meiosis
What is aneuploid?
When the chromosome number is wrong, like one to many or one to few
What is nondisjunction?
the improper separation of chromatids or chromosomes
What are genetic disorders?
When a condition is genetically caused, can be observable
What is a carrier?
a person heterozygous for a condition
What are some genetic disorders caused by dominant alleles?
Polydactyly- having extra fingers or toes
Huntington’s disease- brain tissue breaks down
What are some genetic disorders that are caused by recessive alleles?
Cystic fibrous
Tay-sachs disease- lysosomal storage disease
What allele is the most common to carrier a genetic disorder?
recessive
What is amniocentesis?
When you pull DNA from a fetus and look at karyotype, metabolic and test for some specific genes
What is the “human gene mutation database”?
a catalog of mutant alleles that produce clinical symptoms. over 85000
The closer a gene is to another on the chromosome, the more likely it will….?
travel together during crossing over
The closer two genes on a chromosome are, the more…..?
tightly linked they are
The further away two genes on a chromosome are…..?
the more loosely linked they are
What scientist figured out where genetic information is stored?
Hammerling
What algae did Hammerling work with?
Large-celled marine algae (Acetabularia)
What experiments did Hammerling do?
Amputation- cut off different areas to see which one will grow. only Foot regrew
Grafting- cut up the plant and crafted a different mid section with a different foot, top half grew in like the foot.
What scientist first hypothesize wither it is DNA or protein that holds genetic information?
Griffith
How did Griffith hypothesize wither genetic information is in DNA or protein?
Worked with a pathogen, used different proteins to affect the pathogen and figure out if it still killed or not. Realized that it was in DNA
What two scientist did experiments with Bacteriophages?
Hershey and Chase
What were Hershey and Chase able to find out?
Studied bacteria made only of protein and DNA. Radioactivated both parts. Saw that in new generation only the DNA was radioactive still
What scientist identified DNA as a chemical?
Miescher
What scientist figured out DNA was made of nucleotides but felt that the 4 nucleotides were in equal amounts?
Levene
What was Chargaff’s contribution to the DNA study?
Realized that Levene was wrong and the 4 nucleotides are not in equal amounts. Also realized that A=T and C=G
Who figured out the 3D structure of molecules using x-ray crystallography?
Rosalind Franklin
Who are the men who hypothesized how DNA replicates?
James Watson and Francis Crick
What did Watson and Crick known from past experiments?
DNA is made of nucleotides
Long and Helix
C:G= 1:1
A:T= 1:1
What certain things did Watson and Crick knew that had to be true of DNA?
DNA had to be able to carry lots of traits
DNA had to be able to translate information into protein
DNA had to be able to reproduce
DNA had to be able to make mistakes
Why are outside strands called anti-parallel in DNA?
Because they go in opposite directions. You have the 5 prime and 3 prime strands
When does DNA replicate?
interphase (s phase)
What is the process of DNA replication according to Watson and Crick’s idea?
Unzips
Each nitrogen containing base attracts a new one
each DNA strand is made of an old strand and a new one
Introduced in 1953
What two scientist supported Watson and Crick’s idea that DNA is made of one old strand and one new strand?
Meselsohn and Stahl
How does replication happen?
Uses lots of different enzymes
starts at “replication origin”
What is DNA polymerase III?
Adds nucleotides to new strand of DNA.
Proof reads itself in 3 prime to 5 prime
Can only add nucleotides to an already started chain
What enzyme starts DNA polymerase III? and what is it made by?
RNA primer and made by primase
What does the Helicase do?
unwinds the double helix
What does the primase do?
Synthesizes RNA primer
What does the single-strand binding protein do?
Stabilizes single-stranded regions
What does DNA gyrase do?
Relives torque
What does DNA polymerase III do?
Synthesizes DNA
What does DNA polymerase I do?
Erases primer and fills gap
What does DNA ligase do?
Joins the ends of DNA segments; DNA repair
What are the 2 different strands of DNA that appear during the replication process?
Leading strand- being copied continuously
Lagging strand- copied in segments
What are the DNA segments found on the lagging strand called?
Okazaki Fragments
How are Okazaki Fragments attached?
By DNA ligase
How is DNA replicated in prokaryotes?
Have one circular chromosome
One replication origin per chromosome
Bi-directional- goes in both directions around the circle
How is DNA replicated in eukaryotes?
Have several linear chromosomes.
Multiple replication origin per chromosome
Bi-directional
Slows down because DNA and histones have to be dismantle
What are histones?
Protein found in DNA
What is a centromere?
point of constriction on the chromosome
What is a kinetochore?
attachment site for microtubulars
What happens to the centromere after the S phase?
It is replicated, so there are two centromere molecules
Does each chromatid have its own set of kinetochore proteins?
Yes
What do motor proteins do?
they aid in the rapid final condensation of the chromosomes
What happens in eukaryotic cells during the end of S phase?
they undertake an extensive synthesis of tubulin
What is Tubulin?
the protein that forms microtubules
What is aster?
happens in animal cells.
Its when microtubules reach towards the plasma membrane
What are the two basic mechanisms proposed for the movement of the chromosomes to the cell center?
- assembly and disassembly of microtubules provides the force to move chromosomes
- motor proteins located at kinetochore and poles of the cell pull on microtubules to provide force
Where do the chromosomes line up during Metaphase?
Metaphase plate
What is a polypeptide?
Chain of amino acids
What is a codon?
Three nucleotides that code for an amino acid
What is transcription?
When DNA goes to mRNA
What is mRNA?
messenger RNA
carrier of genetic information to the cytoplasm
large molecules- few 100’s to several thousand nucleotides long
What main enzyme is involved with transcription?
RNA polymerase
What is the process for transcription?
- RNA polymerase attaches to promoter cite
- transcription bubble opens up about 12 nucleotides long
- inside bubble RNA nucl are added to growing mRNA chain
How is mRNA used in prokaryotes?
immediately and as is with no modicfications
How is mRNA used in eukaryotes?
timing can differ, minutes to hours. And there has to be modifications made first
What types of modifications are made to mRNA in eukaryotes?
Cap, Tail and splicing
What is a cap added for on a mRNA?
a 5 prime cap is added for protection
Why is a tail added to a mRNA in eukaryotes?
3 prime poly A tail is added for protection
What is exons?
Expressed nucleotides on a mRNA sequence
What are introns?
Intervening nucleotides on a mRNA strand
How is splicing done?
DNA is in sections, each section alternates between exons and introns
mRNA- introns are clipped out
What is translation?
making mRNA into a protein
what is tRNA?
transfer RNA
around 80 nucleotides long
some parts are single stranded, some double
bottom three nucleotides= anticodon
has a particular amino acid attached to its head
Where is translation done?
ribosomes
what is an aminoacyl?
an amino acid
what is rRNA?
ribosomal RNA
ribosomes are made of rRNA and proteins
What are the three processes of translation?
Initiation
elongation + translocation
termination
What are the three spots inside a ribosome that translation occurs in?
E, P, A
E= exit
P= peptidyl
A= Aminoacyl (amino acid)
What happens in the initiation phase of translation?
- small subunits go into place
- mRNA goes into place
- mRNA has a start codon- AUG
- tRNA appears and attaches. contains amino acid called formyl methionine
What happens in the elongation + translocation phase of translation?
- first tRNA moves to P
-another tRNA moves into A that has an codon that matches
-first amino acid binds with second
-first tRNA moves to E and is kicked out
-Second moves to P
process starts again
What happens in the termination part of the translation?
When amino acid chain is finished, and anticodon appears.
no tRNA can bind to it
everything breaks apart
How is central dogma different in eukaryotes?
post transcriptional modification of primary mRNA
ribosome size
single genes message codes for a single gene
How is central dogma different in prokaryotes?
ribosome size
group genes
group message
What is a group of genes called in prokaryotes?
operon
What is a mutation?
a change in genetic content
some results from a change in gene location
can be positive, negative or neutral
What are the three types of mutations?
Point mutation, chromosome mutation, change in gene postition
What is a point mutation?
a mutation that affects 1 to few mucleotides
What are the causes of point mutation?
mutagens- chemicals, radiation
pairing errors in DNA replication
What are the types of point mutation?
Base substitution- a nucleotide changes to another
insertion- addition of a nucleotide
deletion- loss of a nucleotide
no nonsense mutation- change to a stop codon
triplet repeat expansion mutation- repeating of a codon in excess
What are chromosome mutation?
a mutation where larger section of chromosome is affected
What are some chromosome mutations?
Deletion of chromosome- section is deleted
duplication- section is copied
inversion- section is flipped
translocation- on piece is broken off and attached to another piece
What are some change of gene position mutations?
Transposition- a section of DNA jumps randomly from one location to another (also called jumping gene)
What are the three main causes of mutations?
physical damage by ionizing radiation, physical damage byUV light, chemical damage
What type of ionizing radiation causes mutation?
x-rays and gamma rays
How does ionizing radiation create mutation?
ionized atoms or molecules damage other things. Also called Free Radicals
How does UV light create mutations?
gets absorbed by certain nucleotides
creates a thymine dimer (also can be a c nucleotide)
How does chemical damage cause mutations?
chemicals cause modifications in DNA
What are the 6 main things that regulate genes?
- at initiation of transcription
- processing of primary mRNA transcript (eukaryote)
- Transport of mature mRNA out of nucleus
- Half-life of mRNA
- Protein synthesis
- Post Translational modifications of protein
How are genes regulated at the initiation of transcription?
Affects whether RNA polymerase will bind to promoter
-most efficient regulation
How are genes regulated at the processing of primary mRNA transcript?
uses alternative splicing
How are genes regulated at the transport of mature mRNA out of nucleus?
only 50% of exons leave nucleus
How are genes regulated with the half-life of mRNA?
mRNA gets destroyed by small RNA. All interfere, degrade, cut up mRNA
How are genes regulated by protein synthesis?
Controls wither they are turned on or not
How are genes regulated by post translational modifications of protein?
Changes genes at very end stopping them. very inefficient
Why control gene expression in prokaryotes?
Environmental fluctuation effects what gene gets turned on
Why control gene expression in eukaryotes?
maintain homeostasis
development
right gene must be turned on at right time
What is Mendel’s first law?
Law of segregation. 2 alleles for a gene are segregated and joined together randomly during fertilization
What did Avery, Macleod, and McCarty do?
Realized DNA is responsible for transformation
