Exam 4 Flashcards
What type of sugar is deoxyribose?
a pentose sugar
In 1950, Erwin Chargoff reported that DNA composition varies from one species to the next.
True or False
true
Nucleic acids are polymers specialized for what three things?
- storage
- transmission
- use of genetic information
What is the monomer of nucleic acids?
nucleotides
Are pyrimidines single rings or double rings?
single rings
Which nitrogen bases are purines ?
adenine and guanine
Are Purines single rings or double rings?
double rings
What is the name of the rule that states that in any species there is an equal number of A and T bases, and an equal number of G and C bases?
Chargaff’s rule
Pairing a purine with a pyrimidine results in a uniform width.
true or false?
true
What three things together build a nucleotide?
pentose sugar+ N-containing base+ phosphate group
What two pyrimidines are used in DNA ?
- Thymine
* Cytosine
What did James Watson and Francis Crick (the buttheads) do?
Introduced an elegant double-helical model
Stole the information from Rosalind Franklin
Who was responsible for taking DNA and crystalizing it to take an x-ray photograph?
Rosalind Franklin
How did Rosalind Franklin determine that DNA was a double helix?
By MEASURING the xray crystallography that she had taken of DNA
The Watson-Crick model helped explain Chargoff’s rule. true or false?
true
Why can A not pair with C and G not pair with T?
Because of the amount of hydrogen bonds needed
What does anti-paralell mean?
the two strands going in opposite directions, like two roads going in opposite directions
The two strands of DNA are _____________, so each strand acts as a template for building a new strand in replication.
complementary
In DNA replication, what does the enzyme helicase unwind?
the parent molecule
Once the parent molecule unwinds, the two new daughter strands are built based on what?
base pairing rules
What does a daughter DNA molecule consist of?
One parental strand and one new strand
The new cell that will be made needs a copy of what?
the entire DNA
What is a template?
An existing DNA strand that we can use to copy from or build off of
What type of bond holds the two strands together?
Hydrogen bonds
What Model predicts that when a double helix replicates, each daughter molecule will have one old strand “conserved” from the parent molecule and one newly made strand?
Semiconservative Model
Is DNA synthesis anabolic or catabolic?
anabolic
What four things will the cell need to do DNA replication?
- Energy
- Template
- Enzymes
- Nucleotides (4 Nitrogen bases)
How many strands of DNA are there that must be copied?
48 strands, 24 pairs
DNA is short and thick.
True or False?
Fasle, DNA is very thin and incredibly long
Does DNA synthesis require ATP (Energy)?
Yes, it’s anabolic, it needs energy to build
Name the 4 nitrogen bases used to construct DNA
- Adenine
- Thymine
- Cytosine
- Guanine
Of the 4 bases, which ones are double rings?
Adenine and Guanine
What monomer is used to build into polymers in DNA replication?
Nucleotides
What is copulation?
the act of intercourse to introduce an egg cell to a sperm cell
DNA replication takes one strand and makes it into ___ _______.
two strands
In cells produced by mitosis, are all chromosomes alone or in pairs?
all chromosomes are in pairs
How many PAIRS of chromosomes are found in humans?
23 pairs
Are egg and sperm cells functional without fertilization (without eachother)?
no, they are not functional alone
When DNA first replicates, the two inner strands are still what?
Still attached to eachother, stuck together
During DNA replication, they speak of a “narrow waist” where there is a pinching of the two sister chromatids together, what is this area called?
centromer(e)
Where does the new strand replicate, on the outside or inside?
on the inside
What is the function of mitosis?
to pull apart the chromatids and allow them to complete and become two chromosomes.
If in Mitosis all chromosomes are in pairs, (one from mom, one from dad), what happens with Meiosis?
Meiosis= 1/2 of each chromosome pair
Which helps you repair, mitosis or meiosis?
Mitosis
What is made up of DNA and histone proteins?
Chromatin
Where are eggs and sperm produced?
in the ovaries and testes
How is asexual reproduction in humans done efficiently?
mitosis
How is asexual reproduction in bacteria done efficiently?
binary fission
Asexual reproduction means to what?
clone
Sexual reproduction is done through _______.
meiosis
egg and sperm
Is DNA replication part of interphase or mitosis?
DNA replication is part of interphase
In which part of the stages of mitosis is most of the work done?
prophase/prometaphase
Once the chromosomes look like X’s , they have been replicated (s phase) and are ready (for G2) and are ready for mitosis.
true or false?
true
The centrioles grow microtubules and attach to the chromosome at what part?
the centromer
What protein by the centromer can the microtubules attach to?
kinetochore
In what part of Interphase does DNA replicate?
S phase
In prophase, prophase I, and prophase II, chromatin is condensing into ___________.
Chromosomes
In Prophase (during mitosis), the nuclear envelope and the nucleolus are doing what?
breaking down
Does a replication of centrioles happen during mitosis?
yes
What does Helicase do?
unwinds the parent double helix at replication forks
What does a single-strand binding protein do?
Binds to and stabilizes single-stranded DNA
Which enzyme relieves “overwinding” strain ahead of replication forks by breaking, swiveling, and rejoining DNA strands
Topoisomerase
What is primase for?
synthesizing RNA Primer at 5’ end of leading strand and of each Okazaki fragment of lagging strand
What makes new DNA strands by covalently adding nucleotides to the 3’ end of pre-existing DNA strand or RNA primer
DNA pol III
What enzyme removes RNA nucleotides of primer and replaces them with DNA nucleotides?
DNA polymerase I
Which enzyme is responsible for joining the 3’ end of DNA that replaces primer to the rest of the leading strand and joins Okazaki fragments of the lagging strand?
DNA ligase (hint: ligands join things together)
Which enzyme works first, DNA pol I or DNA pol III?
DNA polymerase III
Replication begins at particular sites called what?
Origins of replication
What happens to the two DNA strands at the origin of replication?
the two DNA strands are separated, opening up a replication “bubble”
Where do origins of replication usually begin?
Where there are multiple A-T sequences in a row together.
Why are A-T sequences a good place for an origin of replication?
Because they are easier to break apart since A-T only have 2 hydrogen bonds
Are there multiple origins of replication or just one?
multiple, this helps it to happen quicker
A eukaryotic chromosome may have hundreds or even thousands of origins of replication.
true or false?
true
Replication proceeds in which direction from each origin, until the entire molecule is copied?
in both directions
The Daughter strand is the ___ strand while the Parental Strand is the ___ strand
new, old
Which strand is the template?
The parental strand
RNA can complimentary base-pair with DNA.
true or false?
true
DNA polymerases can only ADD nucleotides to the 3’ end, they cannot do what?
initiate synthesis of a polynucleotide
they cannot start until a primer is added
We can only add new nucleotides to a 3’ end becuase of the _____ of the enzyme.
shape
Which enzyme can start an RNA chain from scratch and add RNA nucleotides one at a time to the parental DNA template?
primase
When they refer to the RNA primer as short, how many nucleotides long is it?
5-10 nucleotides long
5’ and 3’ has to do with the orientation of what?
the carbons
The 3’ end is continuous, while the bottom strand (lagging strand) has to wait for what?
- for it to unwind
- wait for a primer
- then add nucleotides
At the end of each replication bubble is a replication ____. A y-shaped region where new DNA strands are __________.
fork
elongating
Does helicase untwist the double helix behind or ahead of the fork
ahead of the fork
Does topoisomerase correct “overwinding” behind or ahead of the fork?
ahead of the fork
What two things do most DNA polymerase require?
a primer
a DNA template strand
What is the rate of elongation in bacteria and the rate of elongation in human cells?
bacteria= 500 nucleotides per second humans= 50 nucleotides per second
DNA polymerases add nucleotides only to the free 3’ end, therefore a new DNA strand can elongate only in the _’ to _’ direction
5’ to 3’
To elongate the lagging strand, DNA polymerase must work in what direction?
in the direction away from the replication fork
The lagging strand is synthesized as a series of segments called what?
Okazaki fragments
Okazaki fragments are joined together by what enzyme?
DNA Ligase
The lagging strand can’t add nucleotides continuously, it can only add to a 3’ end so it has to wait for what to happen before it can add a primer?
for helicase to unwind it
What does DNA Polymerase I do to the RNA Primer?
It cuts out the RNA primer and replaces the RNA with DNA nucleotides
Ligase comes in after DNA Polymerase I and does what?
Connects it together so that we have a continuous strand of DNA
What does a DNA Polymerase proofreader do?
Goes down the newly made DNA strand, finds mistakes, cuts them out and replaces any incorrect nucleotides
What happens if a proofreader misses a mistake?
a mutation occurs
What do SOS enzymes do?
repair
What is another name for a mutagenic agent?
a carcinogen
What happens in nucleotide excision repair?
a nuclease cuts out incorrect nucleotide and replaces damaged stretches of DNA
Base pairs code for amino acids.
true or false?
true
When is the only time that mutations can happen?
When DNA is replicating
What is Nuclease
an SOS repair enzyme
When is the only time that a mutation that occurs can effect your offspring?
If the mutation happens while making an Egg or a Sperm
Why do humans evolve so slowly?
they have a low reproduction rate
What are the chances that a mutation can occur?
10^6 or 1 in a million
Cancer is a mistake in DNA replication.
true or false?
true
How many errors occured for someone that gets sickle-cell anemia?
only one error
What does sickle-cell anemia protect from?
malaria
If there were no errors possible, we would never get cancer, but we would also never do what?
evolve
The chromosomes of prokaryotes are what shape?
circular
As DNA replicates, it gets _______.
shorter
Once you cut out the primer at the end, you cannot complete it. During the next round of replication, it will get ___ ___.
cut off
What are the ends of DNA that don’t code for anything called?
telomers
Define Biological age
how many times your cells have divided
Define Chronological age
Age you are in numbers
Telomeres do not prevent the shortening of DNA molecules, but what do they do?
postpone the erosion of genes near the ends of DNA
It has been proposed that the shortening of telomeres is connected to what?
aging
define apoptosis
cell death
Each time DNA replicates, _______ gets cut off
telomer
What is the name of the enzyme that catalyzes the lengthening of telomeres in germ cells?
telomerase
define gametes
egg and sperm cells when they come together
what is another name for germ cell?
stem cell
As we age, what happens to the stem cells ability to produce new cells?
it goes down
Without telomerase, you lose the telomer, and what happend to the cell?
it dies
There is evidence of telomerase activity in cancer cells, which makes the cancer cells somewhat ________.
immortal
What helps condense DNA during cell division?
histone protein
Do normal cells have telomerase? If so when?
yes, but it turns off after gestational period
What is Cancer?
uncontrolled cell division
cells get stuck in a part of the cell cycle
What does cigarette smoke do to the rates of mitosis?
speeds it up
Name some things that can speed up your biological time clock?
- cigarette smoke
- UV exposure
- substance abuse
- life style choices
What best distinguishes living things from non-living things?
the ability of organisms to reproduce
also metabolism
Mitosis is cell division that takes place in what type of cells?
somatic cells
Meiosis produces non-identical daughter cells.
true or false
true
What happens when unicellular organisms do cell division?
division of one cell reproduces the entire organism
What three things does cell division in multicellular organisms result in?
- Production of gametes (egg and sperm)
- Growth
- Repair
Name the two types of cell division in eukaryotes
Mitosis and Meiosis
define genome
all the DNA in a cell
A genome can consist of a single DNA molecule or a number of DNA molecules. Which is common in prokaryotes and which is common in eukaryotes?
single=prokaryotes
multiple=eukaryotes
What are DNA molecules in a cell packaged into?
chromosomes
A Somatic cell is a non-reproductive cell.
true or false?
true (non-sexual)
Is a Gamete a reproductive cell or a non-reproductive cell?
a reproductive cell (sexual)
Gametes have half as many chromosomes as Somatic Cells.
true or false?
true
In Mitosis, Each duplicated Chromosome has __ sister chromatids, which separate during cell division.
2
What is the part of the duplicated chromosome where the two chromatids are most closely attached called
centromere (the waist)
Eukaryotic cell division consists of 2 parts, what are they?
Mitosis, and Cytokinesis
In cytokinesis when the contents of the cytoplasm are divided between the two new cells, is this an equal division?
No
The Mitotic (M) phase consists of what 2 things?
Mitosis and cytokinesis
Where does the cell “do it’s job”?
Interphase
Where does about 90% of the cell cycle take place?
Interphase
Interphase can be divided into 3 subphases, name them
G1
S Phase
G2
The cell grows in all three subphases of interphase, but in which phase are the chromosomes duplicated and DNA replicated
s phase
In which subphase of interphase does the cell grow into its adult characteristics?
G1
Name the phases of mitosis
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
- cytokinesis
In which phase do the microtubules pull apart the sister chromatids?
Anaphase and Anaphase II
Once sister chromatids are pulled apart they are no longer chromatids they are ___________.
chromosomes
In animal cells, cytokinesis occurs by a process known as ________.
cleavage, forming a cleavage furrow
What is the cleavage furrow made of?
microfilaments
A cell plate will eventually modify into what?
a cell wall
What major thing happens in metaphase?
microtubules attach at kinetochore and move the chromosomes to the middle (metaphase plate)
What is the name of the complex of DNA and protein, that eukaryotic cells have, that condenses during cell division?
chromatin
How many sets of chromosomes do somatic cells have?
2 sets
In comparison to somatic cells, how many chromosomes do gametes have?
1/2 as many
Each duplicated chromosome in eukaryotic cells, have 2 ______ __________, which separate during cell division
2 sister chromatids
define cytokinesis
the division of the cytoplasm
What type of cell division are gametes produced in?
meiosis
Meiosis yields nonidentical daughter cells. How many sets of chromosomes do these cells have?
only one set, half as many as the parent cell
What Phase of mitosis does cytokinesis take place during?
Telophase
What is the acronym that Mary used to help us remember the stages of mitosis?
PMAT
Can plant cells have more than one nucleolus?
yes
How big are the two new cells that have just been divided in telophase/cytokinesis?
half the size of the original cell
Where do the two new cells that have just been separated in telophase/cytokinesis need to go next?
Back into interphase to grow up
What happens to the chromatin in Prophase, Prophase I, and Prophase II ?
It begins condensing into chromosomes
During which phase of mitosis have the centrioles /centrosome replicated and gone to separate sides of the cell?
prophase/prometaphase
What do the microtubules of the mitotic spindle do?
They pull and push sister chromatids apart toward opposite spindle poles
What are aster, where are they found?
aster are microtubules emanating (sticking out of) the centrosomes
During which phase do the microtubules attach to the kinetochore and move the chromosomes to the middle?
Metaphase
What builds the mitotic spindle?
centrosomes
In anaphase, what do the microtubules attached to the kinetochore do to pull the sister chromatids apart and toward the opposite poles of the cell?
contract and shorten
In animal cells, cytokinesis occurs by the forming of a cleavage furrow that divides the cell into two parts, what is formed in plant cells that has a similar job?
cell plate
What is a homologous pair?
Both chromosomes of each pair carry genes controlling the same inherited characteristics
A genes specific location along the length of a chromosome is called what?
locus
When you say a cell is 2n it means it’s what?
diploid, it has only 2 sets of information
Of the 23 pairs of chromosomes, the 23rd pair are sex chromosomes, what are the other 22 pairs called?
autosomes
In which one, meiosis or mitosis, do the Homologous Chromosomes pair up in the middle in a line?
meiosis
There are 2 cell divisions.
during which one, mitosis or meiosis?
meiosis
During which phase in Meiosis are there four daughter cells produced?
Telophase II/ cytokinesis
An allele can be dominant or recessive.
true or false?
true
If you have 12 chromosomes total, how many chromatids would you have?
24
Does DNA replication happen during meiosis?
no, its part of interphase and happens before
Do prokaryotes make a mitotic spindle?
no
How many chromosomes does a prokaryote have and what is their shape?
prokaryotes have 1 chromosome and it’s circular
How many origins of replication does a prokaryote have?
only one
Right before a prokaryote splits into two during binary fission, it adds what to the other side before dividing?
another origin of replication (makes a copy)
Is binary fission simple or complex and why?
simple, there is so little DNA in prokaryotes
Mitosis probably evolved from binary fission since there were prokaryotes before eukaryotes.
true or false?
true
Different types of cells divide at different rates.
true or false?
true
Bone marrow cells replicate _______.
quickly
Skin cells replicate _______.
quickly
The eukaryotic cell cycle is regulated by a molecular control system.
true or false?
true
Where are the chemical signals that drive the cell cycle located?
cytoplasm
Hormones are an example of a chemical molecule that does what?
tells cells what to do
In an experiment, what type of cells at different phases of the cell cycle, were fused to form a single cell with two nuclei?
mammalian cells
The sequential events of the cell cycle are directed by what?
cell cycle control system
The cell cycle control system is regulated by both ________ and ________ controls.
internal and external
What directs the cell cycle that is similar to a clock?
cell cycle control system
What is a checkpoint?
where the cell cycle stops until a go-ahead signal is received
A “go-ahead” signal is a chemical release signal.
true or false?
true
Which checkpoint is the most important?
G1
If a cell receives a go-ahead signal at the G1 checkpoint, it will usually do what?
go on to complete the rest of the phases and divide
If a cell does not receive the go-ahead signal at the G1 checkpoint, it will exit the cell and switch into what?
a nondividing state called the G0 phase
Can neurons divide? yes or no and why?
no, because they do not have centrioles and can’t do mitosis
Do you receive more neurons as an adult than you had when you were born?
no, what you have when you are born is what you’ve got
There are two types of regulatory proteins involved in cell cycle control, name them.
- cyclins
* cyclin-dependent kinases (cdks)
What is a cyclin-dependent kinase?
a regulatory protein that’s an enzyme
What is a cell guaranteed to be able to do if it gets past the G2 checkpoint?
mitosis
What does MPF stand for?
a maturation promoting factor
If spindle microtubules have not yet attached to the kinetochore, the kinetochore sends a molecular signal that delays anaphase. What is this an example of?
an internal signal
Some external signals are ______ _______.
growth factors
What are growth factors?
proteins released by certain cells that stimulate other cells to divide (do mitosis)
What are human fibroblast cells responsible for?
making your fibers
What does PDGF stand for?
Platelet-derived growth factor
What is PDGF used to stimulate?
the division of human fibroblast cells
Density-dependent inhibition is an external signal that does what?
stops crowded cells from dividing
In which phase of meiosis do the homologs move toward opposite poles, guided by the spindle apparatus?
Anaphase I
Which phase ends with two identical diploid cells being produced?
Telophase
In which phase do spindle fibers attach to ONE side of the kinetochore?
Metaphase I
What is a substratum?
another cell/something to attach to
What is it called when an animal cell must be attached to another cell in order to divide?
anchorage dependence
What must cells do to make a tissue?
anchor to another cell
Name the two things that control mitosis
- Anchorage dependence
* Density-dependent inhibition
define metastasis
move to another location
Do cancer cells have anchorage dependence and density-dependent inhibition (controls)?
No, cancer cells take away controls
Do cancer cells make it through the G1 phase?
No, they don’t grow up
Can cancer cells break off a tumor and become metastatic?
yes
Does cancer frequently start in Epithelial tissue? Why or why not?
yes, because Epithelial tissues have lots of replication and mitosis so more opportunity for mutations
Cancer cells have a normal cell cycle control system.
true or false?
false, they have an abnormal cell cycle control system
What is it called when a normal cell is converted to a cancerous cell?
transformation
When is a lump called a benign tumor?
If abnormal cells stay at the original site and don’t metastasize
What can malignant tumors do?
- invade surrounding tissues
* metastasize
If the lymph node is sore and you have a fever, is it most likely cancer or an infection?
an infection
What happens during crossing over and what phase does it happen in?
DNA molecules of non-sister chromatids are broken by proteins and are rejoined to eachother.
Prophase I
Does any chromosome replication occur between meiosis I and meiosis II?
no
When chromosomes are still attached at the centromere, DNA replication is complete or not complete?
not complete
Genes are instructions to make proteins.
true or false?
true
What is the information content of DNA in the form of?
sequences of nucleotides (ATCG)
Define genotype
what your genes say you are
example: mary was born a blonde
Define phenotype
what you see, interaction between genes and the environment
example: marys hair colored dark
What are the two stages of gene expression?
- transcription
* translation
What is gene expression?
Making a protein and expressing it
During translation, what is the DNA nucleotide information changed into?
amino acids
Dominant traits and recessive traits are part of which one, your genotype or your phenotype?
genotype and phenotype, although recessive traits cannot be seen with regards to your phenotype
During transcription the DNA is ______ in it’s nucleotide form
copied
During translation, the DNA nucleotides are changed or translated into _____ _____.
amino acids
RNA is the intermediate between genes and the proteins for which they code.
true or false?
true
Transcription produces which type of RNA?
messenger RNA (mRNA)
Translation is the synthesis of a ___________, which occurs under the direction of mRNA
polypeptide
What are considered the sites of translation?
Ribosomes
How does mRNA exit the nucleus to go find a ribosome so that it can do translation
through nuclear pores
In a eukaryotic cell, what separates transcription from translation?
the nuclear envelope
The cellular chain of command is
DNA——-> RNA———–> ________.
Proteins
In transcription, how many sides of the DNA are copied?
one side
In eukaryotes,Pre-mRNA is a single strand. For it to become mRNA what do you have to add to it to help protect it while it’s being transported out of the nucleus?
a cap and poly-A tail
cap to the 5’ end, tail to the 3’ end
_________ attach to the mRNA and translate, tells which amino acids it needs to build a specific protein.
Ribosomes
In bacterial cells, Transcription and translation are done very quickly. The single DNA strand is copied and the ribosomes attach immediately and translate.
true or false?
true
Ribosomes provide the translation for the mRNA transcript.
true or false?
true
How many amino acids are there total?
How many nucleotide bases are there total used in DNA?
20 amino acids
4 nucleotide DNA bases
Ribosomes translate the mRNA transcript in order to build what?
polypeptides (proteins)
How many nucleotide bases does it take to represent an amino acid?
3
DNA is in the code of a nucleotide, mRNA needs to change it into an _____ ____ ____.
amino acid code
What is a Codon?
the triplet code of nucleotide bases
What comes first in the process, transcription or translation?
transcription
In which direction are codons read?
5’ to 3’ direction
Each codon specifies which _____ ____ needs to be placed at a corresponding position along a polypeptide.
amino acid
Which side is the anti-parallel side?
the strand opposite the DNA Template strand
The Primary Transcript is done by mRNA, so what will you see that tells you it’s RNA and not DNA ?
Uracil along the Primary Transcript strand
After mRNA gets the primary transcript from the one side of the DNA, what does the DNA then do?
reseals
One codon can tell us one amino acid, but one amino acid can have many codons.
true or false?
true
How many codons are there total?
64 triplets
How many of the codon triplets, are “stop” signals to end translation?
3 triplets
No codon specifies more than ___ amino acid.
one
How many different “start” codons are there?
1 triplet
What is the name of the “start” codon from our chart?
Methylamine
Which base of the three in a codon, holds the most importance? (if this base is changed, it changes the amino acid used entirely)
first base
Which base out of the three in a codon, is the least important? It is said to have wobble.
Third base
What is the first stage of gene expression?
Transcription
What is RNA synthesis catalyzed by?
an enzyme that pries the DNA apart and hooks together the RNA nucleotides
RNA Polymerase
The DNA sequence where RNA Polymerase attaches is called the ________.
promoter
What is the promoter?
the start of the sequence
The stretch of DNA that is transcribed is called what?
the transcription unit
What is the sequence signaling the end of transcription (end of sequence) called?
terminator
Does RNA polymerase bind to a promoter?
yes
Once the RNA transcript is made, the copy _____ ___ and the DNA reseals (is rewound)
comes off
When does the terminator come into play?
Once the RNA transcript is completed
Name the three stages of transcription.
- ) Initiation
- ) Elongation
- ) Termination
What happens during initiation?
Promoter initiates to start
What happens during elongation?
the addition of RNA nucleotides/ base pairing
What happens during termination?
Signal to stop
What’s another work for the direction of transcription?
“downstream”
What is a complex composed of?
proteins and enzymes
What is the name of the promoter that is crucial in forming the initiation complex in eukaryotes?
TATA Box (hint: start with the tatas)
The promoter binds to a site that has T-A-T-A, why is this a good place to open the strand?
It’s easy to open because there are only 2 hydrogen bonds to break
What do transcription factors do?
mediate the binding of RNA Polymerase and the initiation of transcription
As RNA Polymerase moves along the DNA, it untwists the double helix __ to __ bases at a time.
10-20
Transcription progresses at a rate of __ nucleotides per second in eukaryotes.
40
Can more than one RNA Polymerase attach to the same promoter so that more than one of that specific type of protein can be made at the same time?
yes
Are the mechanisms of termination different in bacteria than they are in eukaryotes?
yes
Is it in bacteria, or eukaryotes, that the polymerase stops transcription at the end of the terminator and immediately falls off?
bacteria
In termination in eukaryotes, the polymerase continues transcription for a while after it’s done being used and eventually falls off.
true or false?
true
Enzymes in the eukaryotic nucleus, modify pre-mRNA (edit the script, take out what’s not needed) before the genetic messages are dispatched to the _________.
cytoplasm
Do Eukaryotic cells modify RNA after transcription?
yes
If I say during RNA processing, both ends of the primary transcript are altered, what am I referring to?
cap and poly-A tail being added
Another alteration that occurs to the RNA transcript after transcription is that usually some parts interior parts of the molecule are cut out and other parts spliced together.
true or false?
true
What is a poly-A tail composed of?
a bunch of adenine
Name the three things the cap and tail do for the mRNA
- help export out of nucleus
- protect it from hydrolytic enzymes (enzymes that will break it down before it’s read)
- help ribosomes attach to the 5’ end
What does the polyadenylation signal do?
signals that it’s time to add the Poly-A Tail
Split genes and RNA Splicing does NOT happen in ___________.
prokaryotes
What are introns?
non-coding stretches of nucleotides, also known as intervening sequences
The part we dont want and need to get rid of, the intruders?
introns
If we want to get rid of the introns, what do we want to keep? The part that will eventually be EXpressed and translated into amino acids
Exons
What does RNA Splicing do?
Removes introns and joins exons creating a continuous coding sequence
What does Intron and Exon shuffling give you?
Different versions of the script
What do Spliceosomes do?
splicing, cutting out introns (intruders), sealing exons together, recognizing splice sites
Does the spliceosome bend the pre-mRNA transcript to cut the introns out?
yes
Enzymes are not the only catalytic molecule. Name the catalytic RNA molecule that functions like enzymes and can splice RNA.
ribozymes
What is it called when some genes can code for more than one kind of polypeptide (protein), depending on which segments are treated as exons during RNA splicing?
alternative RNA splicing
Because of alternative RNA splicing, the number of different proteins an organism can produce is much greater than it’s number of _____.
genes
Exon shuffling may result in the evolution of new protiens.
true or false?
true
A cell translates an mRNA message into protein with the help of what?
transfer RNA (tRNA)
What does tRNA transfer?
amino acid we need to make polypeptide (protein)
Each molecule or tRNA carries a specific amino acid on one end and an _________ on the other end.
anticodon
The anticodon on one end of the tRNA, base pairs with a complementary codon on ____.
mRNA
If each tRNA has to carry a different amino acid, what is the least amount of different tRNA we need
20 at least
Once the primary structure is complete, where does it go next?
to secondary -(beta pleated sheets, alpha helix)
tertiary- (folding, functional, disulfide bridges present)
some go to quaternary
What is the P site ?
peptide binding site, where the polypeptide is built
What is the E site?
the exit site
What is the A site?
The amino acid site, where the amino acid enters
What are spliceosomes made of?
proteins and small nuclear ribonucleoproteins (snRNP’s)
What is the shape of tRNA?
L- shaped
When tRNA is flattened to reveal it’s base pairing, it looks like what?
a cloverleaf
tRNA molecules consist of a single RNA strand and are only about __ nucleotides long
80
Name the two required steps in accurate translation
First: a correct match between tRNA and an amino acid, done by the enzyme
Second: a correct match between tRNA anticodon and an mRNA codon
What is it called when there is flexible pairing at the third base of a codon. This also allows some tRNA to bind to more than one codon?
wobble
What does ribosomal RNA (rRNA) do?
make up the structure of the ribosomes
Ribosomes facilitate specific coupling between ____ anticodon and ____ codons in protein synthesis
tRNA
mRNA
Where are the A site, P site, and E site located?
in the ribosome (large unit)
Where is the mRNA binding site located at on the ribosome?
the small unit
Name the three binding sites for tRNA
- A site
- P site
- E site
The 3 stages of translation are the same as the 3 stages of transcription.
true or false?
true
Which provides less energy, ATP or GTP?
GTP
When elongating the polypeptide chain, _____ _____ are added one by one to the preceding _____ ____.
amino acids
amino acid
Each addition of an amino acid to the elongation chain in translation, involves proteins called __________ _______ and occur in three steps.
elongation factors
During the elongation stage, amino acids are added one by one. Each addition of an amino acid occurs in 3 steps. Name the steps
- codon recognition
- peptide bond formation
- translocation
What is the P sites job?
to hold onto the growing polypeptide chain
When adding the amino acids from the A site to the polypeptide chain in the P site, what type of bond is formed?
peptide bond
Once the amino acid from the A site joins onto the polypeptide chain in the P site, what does the ribosome need to do?
it needs to move/shift
Is energy needed to move the amino acid from the A site to the polypeptide chain in the P site?
yes
When do you know to stop doing the protein synthesis in the ribosome?
you’ll come across the stop codon
Termination of translation occurs when a stop codon in the mRNA, reaches the __ ____ of the ribosome.
A site
When the A site accepts a protein called a release factor, what happens?
the release factor causes the addition of a water molecule instead of an amino acid. This releases the polypeptide
What carries release factors?
stop codon
What enables a cell to make many copies of a polypeptide very quickly?
polyribosomes
When there’s a change in DNA, what is this called?
a mutation
Define point mutations
a chemical change in just one base pair of a gene
mRNA reads in the direction of 3’ to 5’ so that it can produce _’ to _’
5’ to 3’
What are the 2 types of point mutations that can occur within a gene?
- base-pair substitutions
* base-pair insertions or deletions
What type of point mutation would produce a frameshift mutation?
one base pair insertion or one base pair deletion (insertions or deletions)
If there were a 3 base pair deletion, what would be missing?
one amino acid
What kind of mutation has no effect on the amino acid produced by a codon because of redundancy in the genetic code?
silent mutation (usually when the 3rd base has error)
What type of mutation almost always leads to a nonfunctional protein?
nonsense mutations
What happens in a nonsense mutation?
an amino acid codon is changed to a stop codon
Which type of mutation still codes for an amino acid, but not the right amino acid?
missense mutations
Which has a more disastrous effect on the resulting protein, substitutions or insertions and deletions?
insertions and deletions
A physical or chemical agent that can cause mutations is known as what?
a mutagen
Spontaneous mutations can occur during DNA replication, recombination, or repair.
true or false?
true
When an amino acid hooks up with a tRNA, this is called _____ ____ __________.
Amino acid activation
A gene can be defined as a region of DNA that can be expressed to produce a final functional product, either a ___________ or an ___ molecule.
polypeptide
RNA molecule
What is nondisjunction?
If chromosomes don’t separate correctly/ something goes wrong to cause the end cells to not be right. (Extra chromosomes X,Y)
What does trisomy 21 mean and represent?
They got three of the 21st chromosome.
It is Down syndrome
Are there a high amount of genes in the 21 chromosome or a low amount?
Low
The 23rd set of chromosomes determines what?
The sex
Do people that have trisomy 21 often times have heart defects?
Yes
If the micro tubules don’t all connect to the kinetochore completely, what could occur?
Nondisjunction
2n + 1 means what?
You have one too many chromosomes
Nondisjunction can happen at any age in egg or sperm.
True or false?
True
Women are born with all the eggs they’ll ever have.
True or false?
True
Men produce new sperm every day from puberty until death, they continually do meiosis
True or false
True
Prices of your DNA in your cells can actually break off and attach to another chromosome.
True or false
True
What is someone that has XXX?
Super female
What is someone that has XYY
Super male
What does someone with Klines Felters syndrome have?
XXY, male with an extra X
A YO will never _____.
Grow
XO represents someone with what disease?
Turner’s syndrome
Males are much more likely to be colorblind because they need only one _________ _____.
Recessive trait
Both men and females have estrogen and testosterone, what is the only difference?
The levels of each hormone in their bodies
Which has less genetics in it, a Y chromosome or an X?
A Y chromosome has less genes
Who is the father of genetics?
Mendel
Mendel discovered the basic principles of heredity by breeding what?
garden peas
Most genetic traits in humans are _________.
polygenic
Which trisomy has the most severe impact on the health of an individual human?
Trisomy 21
or Trisomy 4
Trisomy 4
What is the main factor that makes it difficult to study a humans genetics?
humans traits are polygenic
What does polygenic mean?
multiple sets of alleles at many different loci (locus)
more than one set of alleles
define true breeding
when the parent organisms only produce offspring with the same traits (same phenotype) as them
When Mendel was doing his research, was this before or after we knew about replication, cell division, mitosis/meiosis, chromosomes, genes?
before
Humans are called diploid organisms because they have ___ _______ at each genetic locus, one inherited from each parent.
two alleles
How many locus and how many sets of alleles does a pea plant have?
1 locus
1 set of alleles
Character varients are called ______.
traits
Each flower has sperm-producing organs called what?
stamens
Each flower has an egg-producing organ called what?
carpel (ovary)
define cross-pollination
fertilization between two plants
In the results from Mendel’s study of pea plants, F1 represents the first set of children. What does F1 stand for?
first filial generation
Is a recessive gene still a gene, and does it still make a protein, even when being masked by a dominant gene?
yes
A recessive gene is still expressed while the dominant overrides it.
true or false
true
How can a pea plant do true breeding on it’s own?
it has both male and female parts (they can self-pollinate)
When Mendel mated two contrasting, true breeding varieties? What was this process called?
hybridization
Who are the true breeding parents of the hybrid offspring?
P generation
What are the hybrid offspring of the P generation called?
F1 generation
When F1 individuals self-pollinate or cross-pollinate with other F1 hybrids, what is produced?
F2 generation
What is Mendel’s ratio in purple to white flowers in the F2 generation?
3 to 1
What Mendel called a “heritable factor” is what we now call a ____.
gene
What is the name for an alternative version of a gene?
alleles
A pair of homologous chromosomes has 2 alleles, one from mom and one from dad, located where?
on the same locus
If two alleles at a locus differ, then out of dominant and recessive, which one determines the organisms appearance and which one has no noticeable effect.
dominant determines appearance
recessive has no noticeable effect
during the production of gametes the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent. What law is this?
Law of Segregation
A diagram for predicting the results of a genetic cross between individuals of known genetic makeup is called what?
a Punnett square
A capital letter represents what kind of allele?
dominant
An organism with two identical alleles for a character is said to be what?
homozygous
for the gene controlling that character
An organism that has two different alleles for a gene is said to be what?
heterozygous
for the gene controlling that character
Unlike homozygotes, _____________ are not true breeding.
heterozygotes
If a genotype is pp, what is it?
homozygous recessive
If a genotype is Pp, what is it?
heterozygous
How can we tell the genotype of an individual when we only know the dominant phenotype?
carry out a testcross
Breeding the mystery individual with a homozygous recessive individual, if any offspring display the recessive phenotype , then the mystery parent must be heterozygous. What is being done here?
a testcross
define monohybrid
heterozygous for one character
What is the law of assortment?
each pair of alleles segregates independently of each other pair of alleles during gamete formation.
What is another word for gamete formation?
meiosis
Alleles/genetic traits on the same chromosome travel together and dont independently assort.
true or false
true
Being somewhere between the phenotypes of the two parental varieties (blended equally) is referred to as __________ _________.
incomplete dominance
When two dominant alleles are both expressed, this is called ___________.
codominance
What occurs when phenotypes of the heterozygote and dominant homozygote are identical?
complete dominance
List the 3 degrees of dominance
- Complete dominance
- Incomplete dominance
- Codominance
Alleles are simply variations in a gene’s nucleotide sequence.
true or false?
true
A dysfunctional enzyme causes an accumulation of lipids in the brain. What disease is this and is it dangerous?
Tay-Sachs disease
yes it is fatal
define polydactyl
extra digits
Are Dominant alleles always more common in populations than recessive alleles?
no.
Is having 5 digits a dominant trait or a recessive trait?
recessive (homozygous recessive)
How many different alleles express bloodtype. What are they?
3 different alleles
- IA
- IB
- i
Why is O- the universal donor?
it has no RH antigens, so it won’t react with other blood types
The enzyme encoded by the IA allele, adds which carbohydrate?
the A Carbohydrate
The enzyme encoded by the i allele adds which carbohydrate?
it doesn’t add a carbohydrate
IAi is the genotype for which blood group?
A
IBIB is the genotype for which blood group?
B
ii is the genotype for which blood group?
O
Most genes have multiple phenotypic effects? This is called what?
pleiotropy
What are responsible for the multiple symptoms of certain hereditary diseases, such as cystic fibrosis and sickle-cell?
pleiotropic alleles
Skin color in humans is a good example of _________ ___________.
polygenic inheritance
What is Polygenic Inheritance?
Many genes that control the same trait
example: eye color, skin color
Hydrangea flowers of the same genotype range from blue-violet to pink, depending on soil acidity. What is this an example of?
Environment controlling/effecting genes
