• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/233

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

233 Cards in this Set

  • Front
  • Back
What is the main chlorophyll associated with photosynthesis?
Chl. A
What are the accessory pigments?
Chl. B, C, and D
What are carotenoids and where do they exist?
Yellow, orange, and reddish pigments, exist in the photosystems.
What do carotenoids do?
Carotenoids act as accessory pigments to assist Chlorophyll A, and absorb free radicals to prevent destruction within the organism.
What are phycobiloproteins?
Phycobiloproteins are blue or red in color and are water soluble.
Where are phycobiloproteins found?
Phycobiloproteins are found in cyanobacteria as well as red algae.
What does an action spectrum show us?
An action spectrum shows how active the pigments are when exposed to different wavelengths (colors) of light. It's functionally similar to absorption spectrum.
What does the absorption spectrum for photosynthesis look like?
Go online
What is the equation for light dependent reactions?
H2O + NADP+ + ADP + P (+ light) ---> NADPH + ATP + O2
What do photosynthetic cells use as electron carriers?
Plants use NADPH instead of FADH2 and NADH as an electron carrier
Where is the reaction center in Photosystem II?
Reaction center molecule in photosystem II is P680
Where is the reaction center in Photosystem I?
Reaction center molecule in photosystem I is P700
How can pigments capture energy?
They have to be arranged in a certain way so they can capture energy and send things to the reaction center.
What is the antenna complex made of and what does it do?
The antenna complex is made of hundreds of pigment molecules which absorb the light energy.
What is the reaction center made of and where is it located?
The reaction center is a trans-membrane protein-pigment complex
What does Z-scheme or Z-diagram mean?
It is the process of light-dependent reactions.
Describe the first process of light-dependent reactions.
Light is received by the antenna complex in Photosystem II, electrons sent to reaction center, passes it b6-f complex, which takes an electron and pumps out a proton, then passes electrons to Photosystem I.
What role does water play in light-dependent reactions?
It splits and donates electrons when things need to release electrons. This releases oxygen, and scientists theorize that this is how the earth was originally oxygenated.
What does the b6-f complex do?
It receives electrons from the reaction center, and takes the electrons and pumps out protons, then passes electrons to photosystem 1.
What happens in photosystem I?
The process that happens in photosystem II repeats itself. So electrons go through the reaction center, passed to b6-f complex, protons are pumped out
Is the process that occurs in photosystem I a cycle?
No. It is referred to as noncyclic photophosphorulation.
What happens to the protons that the b6-f complex has pumped out?
Protons that are pumped out accumlate in saces. This proton gradient fuels ATP production in a similar way to respiration.
What happens to the low energy electrons that are left over after light-dependent reactions?
Low energy electrons may be sent back to the first part of the electron chain, referred to as cyclic photophosphorulation.
Where do light-independent reactions take place?
Light independent reactions occur in the stroma (inner part of chloroplasts).
Where is the stroma?
The stroma is located in the inner part of chloroplasts.
Are light-independent reactions truly light-independent?
Recent findings show that enzymes in the system are activated by light.
What is the formula of light-independent reactions?
3CO2 + 9ATP + 6NADPH + Water -> 1G3P + 8P + 9 ADP + 6 NADP+
What do light-independent reactions use?
They use ATP + NADPH made in light-dependent reactions.
Describe the process of light-independent reactions.
1. 3 CO2 combine with 3 5-carbon sugars, and rearrange into 6 3-carbon pieces. 5C sugar = RuBP
2. 6 ATP energize the 3-carbon pieces, and further down, 6NADPH energize them, and results in 6 3-carbon sugars (G3P), which are very high energy
3. One G#P goes to produce glucose (this require twice through the cycle, because G3P is a 3 carbon sugar and glucose is a 3 carbon sugar)
4. The rest of the G3P use 3 ATP to convert back to RuBP and restart the cycle.
What is the enzyme that facilitates light-independent reactions?
Rubisco facilitates light-independent reactions, which acts very slowly. Can only make 3 5-C sugars rearranged into 6 3C pieces per second.
What does G3P do after it has gone through light-independent reactions?
G3P can go to make glucose, fructose, sucrose, etc.
What characterizes C3 plants?
C3 stands for 3-carbon plants. They go through this process of light-dependent reaction and Calvin Cycle. C3 plants use Rubisco as an enzyme. Most plants are like this.
What characterizes C4 plants?
C4 plants have PEP carboxylase instead of Rubisco as an enzyme.
-They have a high affinity for CO2 and photorespiration doesn't occur.
- They can capture CO2 even at a very low CO2 concentration. Stomata stay closed more often, and thus there is less water loss.
-4C sugar is taken deep into the plant into the bundle-sheath cell, where it is broken down into CO2, and the Calvin cycle occurs
What can go wrong in C3 plants?
RuBP can combine with O2 instead of CO2. If this happens, then sugar is not made. This can happen if there is too much Oxygen and not enough CO2, or the temperature is too high.
Why does a high temperature affect C3 plants?
At 25 degrees C, about 20% of sugar that is made is lost. If it's hot, stomata close, CO2 drops, and photorespiration occurs.
What is photorespiration?
Photorespiration is when there is too much oxygen and not enough CO2. It happens in C3 plants
Does any rubisco exist in C4 plants?
Yes. Rubisco still exists deep in the plant, however because PEP carboxylase sucks up so much CO2 and sends it down, this is no big deal.
What are some examples of C4 plants?
Corn, sugarcane, crabgrass
What is similar and dissimilar about photosynthesis and respiration?
-Both produce ATP through chemiosmosis
Plants: chemiosmosis takes place in chloroplasts, protons accumulate in thylakoid sacs
Respiration: chemiosmosis takes place in mitochondria where protons accumulate in intermembrane space.
-Both use electron carriers
Respiration: FADH2 and NADH
Photosynthesis: NADPH
What is a ligand?
A signal that is received by receptor proteins
What are the three stages of sending and receiving signals?
1. Reception- when the receptor protein receives the signal
2. transduction- the process in between reception and response. The protein sets in motion a chain of events (usually several steps) that eventually leads to the cellular response.
3. cellular response- when something actually happens as a result of the signal
What characterizes a paracrine signal?
A paracrine signal is very local, the signal does not go a long way. Fig 9.2
What characterizes endocrine signaling?
Hormones are involved in endocrine signaling, and the signal is sent to a more distant location.
What characterizes synaptic signaling?
Synaptic signaling signals from a nerve cell. It is very local.
What characterizes direct contact?
Direct contact is communication through cell junctions, as discussed before.
What is the type of signaling where hormones are involved, and the signal is sent to a more distant location.
Endocrine signaling.
What signals from a nerve cell and is also very local?
Synaptic signaling
What are some characteristics that make ligands so useful in intracellular reception?
Ligands are hydrophobic, and so interact well with the inside of the membrane. They are lipid soluble and so can go through the cell membrane.
How do ligands act as gene regulators?
The cellular response when ligands act as gene regulators is that a gene would be turned on or off.
What are the three kinds of intercellular reception?
Enzyme receptors, chemically gated ion channels, and G protein-couple receptors (GPCR's)
How do enzyme receptors work?
When a ligand bonds to the receptor on the outside, the enzymatic portion on the inside of the cell is activated.
How do chemically gated ion channels work?
A protein forms a channel that fits a certain ion, but the channel only opens up when the signal is received
What does GPCR's stand for?
G protein-coupled receptors
How do GPCR's work?
On the outside there is a signal binding location, and on the inside there is G-protein. When the signal binds, there is a conformational change. The G-protein has a GDP attached, and is phosphorylated when the signal binds, turning it into GTP.
Fig. 9.11
How do enzyme receptors work when they are working as a kinase?
This enzyme often behaves as a kinase. Kinases phosphorylates (add a phosphate group to) another protein. Some kinds may phosphorylate each other when the signal is received, after which the enzymes may phosphorylate something else for a cellular response.
What are a few second messengers and in what organisms are they found?
cAMP used in animal cell communication, Ca++ Calcium ions used by plants and animals
What does cAMP stand for?
Cyclic Adenosine Monophosphate. It's like ATP and ADP, but with only one phosphate
How is cAMP engaged?
Fig 9.13. Signal comes in, activates GDP protein, creates GTP which activates the production of cAMP, which activates PKA, engages another Kinase, and leads to cellular response.
How is Ca++ engaged?
Fig 9.15. Enzymes involved in messenger system cause calcium to be released, which bond to proteins and cause the cellular response.
What is amplification?
Activator sets in motion increasing number of Kinases, which eventually trigger lots of reaction proteins. This expedites the reactions.
What is a diploid?
When chromosomes exist in pairs within cells
How many chromosomes do humans have?
Humans have 23 pairs of chromosomes in each cell, with the exception of gametes.
What are histones?
Histones are the primary proteins involved in chromosomes. DNA coils around histone, which all repeat and coil up into chromosomes
What is euchromatin?
When a cell is not dividing, the DNA usually comes uncondensed for use. The DNA is usable.
What are heterochromatin, what are its uses, and where it found the most?
When DNA remains coiled and unusable it is called heterochromatin. More heterochromatin exists in the centromere, so heterochromatin may be a structural function. It could also be for gene regulation, keeping genes that are not currently needed out of use.
What are homologous chromosomes?
Pairs of chromosomes that are usually drawn side by side that have the same size and shape.
What is the center of the chromosome called?
Centromere
What is the the area on either side of the center of a chromosome called?
Kinetochore, where microtubules attach to pull apart chromosomes.
What is cohesin?
Cohesin is protein material that holds chromatids together at the centromere.
When chromosomes do not come in pairs, what are they called?
Haploids
What is a karyotype?
A karyotype is a cell's chromosome array. It is useful because not all chromosomes look alike.
Define cell cycle
The cell cycle is a process of growth and cell division in which most cells engage.
What is the order of phases that the cell cycle goes through?
Interphase, Prophase, Metaphase, Anaphase, Telophase (IPMAT)
What is involved in interphase?
G0 phase (resting phase), G1 Gap phase, S phase, and G2 Gap 2 phase
What happens in the G1 phase?
Things are produced
What happens in the S phase?
DNA is produced
What happens in the G2 phase?
Lost of things are produced within the cell. Molecules are made and organelles are assembled. Microtubules are assembled into spindles to pull things apart
What is mitosis?
Mitosis is division of one nucleus into 2 nuclei.
Who discovered mitosis?
Fleming in 1879 which he was studying Salamanders.
What happens in mitosis?
Interphase (must be completed), prophase, metaphase, anaphase telophase.
What happens in Prophase?
1. Condensed chromosomes begin to appear, nuclear membrane begins to disappear. The nucleolus also disappears.
2. Miotic spindles begin to form
3. Microtubules start or organize, may extend across middle, and some may stick out at ends.
What happens in Metaphase?
Chromosomes line up in the middle of the cells, and then they are properly attached to spindle fibers
What happens in Anaphase?
Sister chromatids separate from one another and cohesin must disintegrate
What happens in Telophase?
-Sister chromatids are now chromosomes, and they separate out and reach their final destinations
-This is in essence the opposite of prophase. Nuclear membrane reappears, etc.
What is cytokinesis?
Cytokinesis is one cell dividing into 2 cells. This is when cytoplasm actually divides.
How does cytokinesis happen in plant cells?
In plants, the cell wall prevents the cell from just squeezing off. A barrier must form in the center. Microtubules line vesicles up across the middle of the cell to form this barrier (cell plate).
What is the cell plate?
The barrier in the center of two dividing cells. Microtubules line vesicles up across the middle of the cell to form this barrier
How does cytokinesis happen in animal cells?
The cell membrane pinches in and divides into two cells. Actin in involved in this pinching.
How is the cell cycle controlled?
The cell cycle has 3 checkpoints.: G1/S, G2/M, and Spindle
How does G1/S control the cell cycle?
The checkpoint happens near the end of the G1 cycle, and before the S portion starts. It decides whether the cell is ready to continue. If not, if goes into G0 phase of rest.
What does the G1/S checkpoint check for?
It asks if the cell is large enough, and has enough nutrition to continue. Also looks for DNA correctness.
How does G2/M control the cell cycle?
At the end of G2 portion of the cycle.
What does G2/M check for and how does it act if it finds an error?
The G2/M checkpoint asks about DNA integrite. Did dynthesis go according to plan? If DNA errors are found, the p53 gene makes p53 protein as a gene product. DNA repair will occur if possible. If errors cannot be fixed, cell will undergo apoptosis.
What is cell suicide?
Apoptosis.
What does p53 gene do?
p53 makes p53 as a gene product and repairs if possible.
How does the spindle checkpoint work? What is it checking for?
The spindle checkpoint happens during metaphase, when the spindles are lined up. It asks whether or not chromosomes are properly attached to the spindles.
What are CDK's?
CDK stands for Cyclin-dependent protein Kinases.
How many control sites do CDK's have, where are they, and what do they do?
CDK's have 3 control sites: 2 locations for phosphorylation (one to activate and one to deactivate) and one site for Cyclin to attach and activate the Kinase
What activates the CDK's?
Cyclin! (Cyclin-dependent protein Kinases! ...duh)
How do CDK and G1/S checkpoint work together?
In unicellular organisms, it grows to the point where the cell must ask if it is big enough to engage in mitosis. It determines this by determining the ratio of cytoplasm to DNA. When it is big enough, cyclin is produced, and attached to CDK, at which point the cell cycle is promoted.
What does PDGF? What does it do?
PDGF is platelet derived growth factor. Platelets detect a wound, send message to fibroblasts in blood (branching cells, form intercellular matrix in blood), which will begin to divide.
What does the G1/S checkpoint have to do in multicellular organisms?
1. Positive and inhibitory system
2. Senses the density of cells around them
3. The denser the cells are, the more inhibitory signals are sent, which will stop cell division
4. Growth factors are mostly paracrine signals.
What kind of signal are growth factors?
Growth factors are mostly paracrine signals. There must be numerous kinds of growth factors in order to activate cell division.
Who discovered meiosis (and when)?
Van Beneden discovered meiosis in the 1880's when he was studying roundworms.
What is syngamy?
It is fertilization. It's the fusion of 2 gametes to regain the full chromosome count.
What is the fusion of 2 gametes called?
Syngamy.
What is the fertilization diagram?
1N cell + 1N cell --> 2N cell
What is the meiosis diagram?
2N cell --> 4 1N cells
What is gamete production called?
Gametogenesis
What happens in the haploid life cycle?
1N organism produces 1N gametes through mitosis. 1N gamete finds another 1N gamete and 2Z zygote is formed through fertilization. Meiosis occurs to turn the 2N zygotes into 1N spores, which turn into 1N organisms through mitosis
Define spore.
A spore is a cell that develops on its own, without having to fuse with another gamete.
Describe the life cycle of an organism who goes through 1N and 2N life cycle in an alternation of generations.
1N organism makes 1N gametes through mitosis. The 1N gametes combine to form a 2N zygote through fertilization. The 2N zygotes form into adult organisms through mitosis. The 2N forms 1N spores through meiosis, which turn into 1N organisms through mitosis and the cycle repeats.
In organisms that alternate generations, what is the 1N organism that makes gametes called?
It is called the gametophyte generation.
In organisms that alternate generations, what is the 2N organism that makes spores called?
It is called the sporophyte generation.
What is the formula for meiosis?
1 2N cell ---> 4 1N cells.
What are 1N cells called?
Either gametes or spores.
What is the longest stage of meiosis I and how much time is spent in it?
Prophase I is the longest stage. 95% or meiosis occurs in Prophase I and Metaphase I.
What is the synaptonemal complex?
The synaptonemal complex causes the tetrad to attach itself.
What happens in Prophase I of meiosis that is different from Prophase in mitosis?
Homologous chromosomes pair with one another, resulting in 4 chromatids, also known as a "tetrad". The pairing of chromosomes will allow for "crossing over". Chromosomes cross over, then break off, causing part of one chromosome to attach to the other, and vice versa.
What is the difference between chromosomes and chromatids?
Once chromatids separate in Anaphase II, they are known as chromatids. Chromosomes are independent entities with genetic material, whether it be 1 chromatid or 2.
Compare mitosis and meiosis.
Mitosis:
1. 2 cells are formed
2. 1 division takes place
3. pairing of homologous chromosomes does not take place
4. "crossing over" does not take place
5. starting with 2N, 2N will result
6. starting with 8N, 8N will result
7. resulting cells
Meiosis:
1. 4 cells are formed
2. 2 divisions take place
3. pairing of homologous chromosomes takes place
4. crossing over takes place
5. starting with 2N, 1N cells will be the result
6. starting with 8N, 4N will result
7. Resulting cells are not identical
What are the advantages and disadvantages of asexual reproduction?
The advantages are that it's "cheaper", requires less energy and effort. Disadvantages are that offspring are similar/identical to parents. This makes it less fit for natural selection.
Tell me about Gregor Mendel
He lived from 1822-1884. Was an Austrian monk. Grew up on a farm in what is now the Czech Republic that had been in his family for many years. After high school, he moved on to a Philosophical Institute and was recommended by his teachers to join a monastery in 1843. After studying theology at the monastery, he went to the University of Vienna, studying Math and Science. Ended up teaching. While teaching, he studied the breeding of peas. Gave an oral report in 1865 and a written publication in 1866. The written publication was not well received. Nobody really cared (probably because it was boring). Soon after this, he became the Abbot of the monastery, which ended his work with peas. He died in 1884, before his work was rediscovered (around 1900). His works were rediscovered separately by 3 European scientists.
Why was Gregor Mendel so successful?
Trained i math, very quantitative. (29,000 plants!). Trained in science. Peas were a good call on his part.
Why were peas such a good plant for Mendel to use?
They were small, so he could grow a lot of them. They grow fast. Flowers contain both male and female portions, thus they can be self-pollenated or cross-pollenated. Earlier had been done on peas, so he could have consistent material to work with.
What were the 7 traits that Mendel published on?
Flower color, seed color, seed texture, pod color, pod shape, flower position, and tall vs short (size).
Describe Mendel's experiment regarding flower color.
He crossed purple flowered and white flowered plants (P generation). F1 generation (F= filial), all flowers were purple. This created the ideas of dominant and recessive traits. F1 was bred with one another, to create F2 generation. F2' results were approximately 3 purple: 1 white. Self-crossed the F2 generation, crossing whites with white and purples with purples. The results were white flowers in F2 produced only white flowers. Some purple flowers only produced purples, some produced 3 purple and 1 white. The actual ration is 1DD: 2Dr: 1rr (D= dominant, r= recessive)
What was Mendel's conclusion as to how traits are inherited?
He concluded that organisms have 2 hereditary factors, from which he determined that each gamete would get 1 factor. Of course this conclusion is not all right.
What happened when Mendel cross his F1 generation?
He got the ratio 1 DD: 2Dr: 1 rr
What are homologous chromosomes?
Homologous chromosomes are pairs of chromosomes carrying similar genetic information.
What is a gene?
A gene helps control a specific trait. They are found at particular location on a chromosome.
What is an allele?
Allele is an alternative form of a gene. Ex. There are alleles for purple and white flowers, or round and wrinkled seeds. Alleles are what we use upper and lower case letters to express.
Define the difference between chromosomes, genes, and alleles?
Chromosomes have genes and genes have different alleles.
What is a locus?
A locus is a position of a gene on a chromosome.
What is a genotype?
A genotype is the allele combinations that create a specific trait. RR= homozygous dominant. Rr= heterozygous. rr= homozygous recessive.
What is the phenotype?
A phenotype is the physical characteristics of an organism.
What does a probability of 0 mean? What does a probability of 1 mean?
A probability of 0 means that something definitely won't happen. A probability of 1 means that something definitely will happen.
Define independent event.
An independent event is when one event does not affect another event.
Define mutually exclusive event.
A mutually exclusive event is an event that cannot happen at the same time as another event.
What is the rule of addition?
If two events are mutually exclusive, the likelihood of either one is the sum of their individual probabilities. Ex. Pp x Pp ---> PP + Pp + pp. Probability of dominant phenotype= probability of PP is 1/4 and that of Pp is 1/2. Therefore, the probability of a dominant phenotype is 3/4.
When would you use the rule of addition?
You would use the rule of addition in the case of two mutually exclusive events.
What is the rule of multiplication?
The rule of multiplication is the probability of 2 independent events both happening is the product of their individual probabilities. Ex. Pp x Pp ---> PP + Pp + pp. The probability of recessive phenotype: needs pp. Must receive p from father and p from mother. p from father is 1/2, p from mother is 1/2. Therefore, the probability of pp is 1/4.
What is a monohybrid cross?
A monohybrid cross is when you cross two of the same genotype/ Ex. Rr x Rr = 1RR : 2Rr :1rr.
What is Mendel's first law?
Mendel's first law is the Law of segregation. The law of segregation is that pairs of factors separate when making gametes, them come back together again.
How would one perform a test cross and why would one perform a test cross?
A test cross determines if an animal is SS or Ss. For example, lets take spots on cows. Spotty = S, non-spotty = s. A spotty cow could be SS or Ss. So you breed the unknown cow with ss. If all offspring are spotty, the unknown cow was SS, and if there are non-spotty, then it was Ss
What is a dihybrid cross and when would you use it?
A dihybrid cross is when 2 traits are observed simultaneously. Ex. Round and wrinkled seeds and yellow v green seeds. Breed and RRYY (homozygous dominant in both traits) with rryy (homozygous recessive in both traits). F1 is entirely RrYy. F2 is 9 Round/Yelllow: 3 wrinkled/yellow : 3 round/green : 1 wrinkled/green
What is Mendel's second law?
Mendel's second law is the law of independent assortment. The law of independent assortment states that pairs of factors separate independently of one another in meiosis.
What is incomplete dominance?
Incomplete dominance is when the heterozygote is intermediate between the homozygotes in phenotype. Ex. some white and pink flowers breed to produce pink flowers in the F1 generation. In the F2 generation, the ration is 1 red: 2 pink: 1 white
What is pleiotropy?
Pleiotropy is when one allele has more than one effect on the phenotype. Ex. Cystic Fibrosis- numerous issues are caused by one altered allele.
What is the result when many genes act to influence a single trait?
Continuous variation is the result.
What are codominant alleles?
Codominant alleles are when more than one allele shows dominance. Ex. ABO blood types. A, B, AB, O phenotypes for blood. Genotypes: based on alleles IA, IB and i. A and B are antigens. A blood has antibodies for B, and vice versa. AB has neither, O has both.
What does the IA allele (blood type) do?
The IA allele has an enzyme that adds GALACTOSAMINE to lipids.
What does the IB allele (blood type) do?
The IB allele has an enzyme that adds GALACTOSE to lipids
What are autosomes?
The 22 pairs of chromosomes that are not sex chromosomes.
Which is smaller: X chromosomes or Y chromosomes?
Y chromosomes are much smaller than X.
How many genes does the Y chromosome contain?
The Y chromosomes contains 78 genes.
How do errors in the chromosome number occur?
Usually occur in meiosis
What is an aneuploid?
An aneuploid is where there are one too many or one too few chromosomes.
What is nondisjunction?
Nondisjunction is when there is an error in the movement of chromosomes during meiosis.
What is an example of a disease that happens because of aneuploidy?
Down syndrome is when there are 3 copies of chromosome 21.
What defines a genetic disorder?
A genetic disorder is when some condition is genetically caused, and there is a reasonable probability of it occurring again.
Are most genetic disorders dominant or recessive alleles?
Most of them are caused by recessive alleles, but there are a few that are based on dominant alleles.
Tell me about cystic fibrosis.
-It rides on a recessive allele.
-1/2500 caucasian
-it's caused by chlorine ion transport errors
-gene therapy is an attempt to fix this
-puts a good allele into a person with a nonfunctional allele
Tell me about Tay-Sachs disease.
-It's a lysosomal storage disease, caused by missing lipid digesting enzymes
-Usually lethal after 3-4 years
Tell me about hemophilia
-It involves slow or lack of blood clotting.
-Can be caused by an error in a number of proteins, and thus the disease varies slightly.
Tell me about sickle-cell anemia.
-It is caused by an error in the beta-chain of hemoglobin (which has 2 alphas and 2 betas)
-Prevalent in Africa because sickle-cell anemia carriers are resistant to malaria
-"Heterozygote superiority", and its application to natural selection
What causes cystic fibrosis?
Cystic fibrosis is caused by chlorine ion transport errors.
What causes Tay-Sachs disease?
Tay-Sachs disease is caused by missing lipid digesting enzymes.
What causes hemophilia?
Hemophilia is caused by an error in a number of proteins, and thus the disease varies slightly.
What causes sickle-cell anemia?
Sickle-cell anemia is caused by an error in the beta-chain of hemoglobin (which has 2 alphas and 2 betas).
What do so many Africans have sickle cell anemia and what is this an example of (natural selection wise)
It is prevalent in Africa because sickle-cell anemia carriers are resistant to malaria. This is an example of "heterozygote superiority" and its application to natural selection.
What is the human gene mutation database?
It is a catalog of mutant allele cause clinical symptoms.
How many human gene mutations are logged in the database, and what are some prevalent characteristics of them?
28,000 are logged, a lot of which are related to hemoglobin. Most are recessive. Most are caused by relatively small errors: 1-20 base substitution. 60% are caused by 1 base substitution, another 20% are 2-20 base substitutions.
What are the most prevalent errors in base substitutions?
Most are caused by relatively small errors: 1-20 base substitution. 60% are caused by 1 base substitution, another 20% are 2-20 base substitutions.
What is a carrier?
A carrier is someone who is heterozygous for a disease and so therefore can pass on a disease.
What are "linked" genes?
Linked genes are genes that are on the same chromosome.
Explain what a "transcription bubble" is and how big it is.
A transcription bubble is around 12 nucleotides long. In this transcription bubble, mRNA nucleotides are added to match the DNA nucleotides, and the message is transcribed.
How fast does transcription happen?
The process goes fairly slowly, 50 RNA nucleotides per second are added.
What is elongation?
Elongation is the process of adding nucleotides. No primer or proofreading is necessary.
What is termination and how does it work?
Near the end of the message, the RNA nucleotides pair with each other, and the mRNA strand loops together, disrupting the process which makes it all fall apart and the RNA strand comes off the DNA. Last nucleotides that are added are Uracil, which don't bond as well, which also helps make the whole thing fall apart.
Define transcription unit.
A transcription unit is the distance from the promoter to the terminator on the DNA.
What does mRNA do?
mRNA codes for protein.
When does mRNA code for protein?
mRNA codes for protein directly after transcription in prokaryotes, but in eukaryotes, 3 things must be done to the mRNA before use (Post-transctiptional modifications).
What are the 3 post transcriptional modifications?
1. 5' cap is added on one end of the strand (this cap is GTP)
2. Poly-A tail is added to the other end of the strand
3. DNA is functionally divided, alternating between E1, I1, E2, I2, E3, I3, E4 when E-exon, I= Intron. Introns are only found in eukaryotes.
What are introns are where are they found?
Introns are found only in eukaryotes. They are non-coding bits of DNA.
How does DNA get transferred to the mRNA to make it the primary transcript?
1. Introns must be removed, so only Exons are left (Introns are pinched off and snipped out).
2. After introns are removed, the result is the mature mRNA transcript.
How many introns do genes have? In the human genome, how many or our genes are introns and how many are exons?
Genes have 0-50 introns, which may have anywhere from just a few nucleotides up to 7500 nucleotides. The human genome is around 24% introns, and 1-1.5% exons.
What is translation trying to do?
Translation is making the mature mRNA code for protein.
How does mRNA lead to protein?- what are the three steps?
Initation, Protein making, and Termination
What do aminoacyl-tRNA synthetases do?
They are enzymes that ensure the right amino acids are paired up with the tRNA.
How long is tRNA?
tRNA is about 80 nucleotides long.
What are the two ends of tRNA and what do they do?
tRNA has two ends, an amino acid acceptor end and an anticodon end. On the anticodon end, 3 nucleotides are exposed. There are complementary to codons nucleotides) on the mRNA.
How much of the RNA in our cells is rRNA?
About 80% of the cellular RNA is rRNA (ribosomal RNA)
Describe the process mRNA goes through during initiation.
1. A small ribosomal subunit comes into position, and the mRNA positions itself on it.
What does the ribosome structure look like that codes the mRNA?
There are 3 locations on the ribosome that matter. E (Exit) where things fall off, and P (peptidyl) which has to do with the peptides and where it is building up, and A (Amino-acyl), where amino acids enter.
How do tRNA and ribosomes interact to make proteins?
tRNA with Amino Acid enter P site on the ribosome. This is attached to a special amino acid called fmet and has the anticodon UAC. Different tRNA's enter with amino acids that correspond with the codons on the mRNA (the anticodon end also corresponds with these codons).
How does termination work during translation?
Termination is when a stop codon is reached, and the process stops. A release factor enters the system and the whole thing falls apart.
How is mutation caused?
Mutation may be caused by movement in genetic information. May be positive or negative in effect, however a lot of them are neutral.
What are the different types of mutation?
Point mutation and chromosomal mutation.
What is point mutation, what does it affect, and what causes it??
Point mutation affects 1-few nucleotides. It causes mutogens and may be caused by chemicals or radiation, which can be natural or human triggered.
What are the different types of point mutations?
-Base substitution (ex. ATA mutates into ATCA)
-Deletion: (ex. ATA mutates into AT
-Insertion (ex. ATA mutates into ATCA)
What are the frameshift mutations?
Insertion and deletion are called frameshift mutations because they change the reading frame of the nucleotide triplets, and mess it up for everything.
What is a nonsense mutation?
A nonsense mutation is when something is changed in to a stop codon and proteins are shortened.
What is a triplet repeat expansion?
Triplets such as ACA duplicate themselves.
What is chromosomal mutation?
Ex. Deletion, duplication, inversion, etc. of a whole chunk of a chromosome.
What causes chromosomal mutations?
Chromosomeal mutations may be due to a movement of a piece of DNA. Ex. Transposition/Jumping genes, which a "transposon" moves somewhere randomly. It can be caused by ionizing radiation (X-rays, gamma rays). High energy wavelengths cause free radicals to form, which interact with other molecules and damage them. UV light also causes them. Lower energy wavelengths, and don't cause free radicals. UV light is absorbed by T and C nucleotides. If they are adjacent, they ay bind to one another and form a "dimer". This causes a kink in part of a DNA strand. Chemicals can also cause it. Can be many examples of this taht can take many methods of action. One example is changing nucleotides, causing enzymes to not recognize the nucleotides.
How does UV light cause chromosomal mutations?
Lower energy wavelengths don't cause free radicals. UV light is absorbed by T and C nucleotides. If they are adjacent, they may bind to one another and form a dimer which causes a kink in part of DNA strand.
How do Ionizing radiation (X-rays, Gamma rays) cause chromosomal mutations?
High energy wavelengths cause free radicals to form, which interact with other molecules and damage them.
What are the mechanisms of regulating gene expressions?
1. At the initiation of transcription
2. Processing of he primary messenger RNA transcript
3. Transport of the mRNA out of the nucleus
4. Half-life of mRNA
5. small RNA's
6. Protein synthesis (translation)
7. Post-translation control
What is the most important mechanism of regulating gene expression and how does it work?
The most important mechanism of regulating gene expression is at the initiation of transcription. It affects if the RNA polymerase binds to the promoter or not.
How does processing of the primary messenger RNA transcript help regulate gene expression?
It can be spliced together in different ways.
How can a cell regulate gene expression in the transport of the mRNA out of the nucleus (through nuclear pores)?
1. Only roughly 50% of mRNA leaves the nucleus.
2. Is it selective?
What is the significance of the half-life of mRNA?
Prokaryote mRNA lasts on average 3 minutes. In Eukaryotes, the messages last from minutes to hours.
What is the significance of small RNA's?
Micro-RNA's (miRNA) tend to hind or cleave messages. Small-interfering RNA's (siRNA) degrade messages.
What do micro-RNA's do?
miRNA binds or cleaves messages.
What do siRNA do?
Small-interfering RNAs degrade messages.
How can a cell regulate gene expression in Protein synthesis (translation)?
It can affect initiation (determining whether or not it starts).
How can a cell regulate gene expression in post-translational control?
Control of the actual protein that is produced.
Why is it important that prokaryotes regulate their gene expression?
In Prokaryotes the genes that are turned on depend on their environment. The food that's around affects which genes are turned on and off.
What is it important that eukaryotes regulate their gene expression?
It's important to regulate their gene expression because in order to keep internal conditions at homeostasis, genes need to be turned on or of in order to maintain it. Also it affects developmental issues and apoptosis.
What is a reason why both eukaryotes and prokaryotes need to regulate gene expression?
Efficiency. It would be a mess if cells were to make all proteins all the time, and it would cost too much energy.
How does a cell regulate transcription?
1. Regulatory sequence. Regulates the coding of genes, typically ahead of coding region (closer to 5' end of DNA as opposed to 3' end. Somewher ein the regulatory sequence is the promoter.
2. Coding region on DNA contains genes that code for the protein.
3. Need RNA polymerase in the first place.
4. Transcription factors- proteins that bind to the regulatory region with promote or inhibit the RNA polymerases's action
How is DNA regulated? (how do proteins/transcription bind with it)?
In the MAJOR GROOVE of the DNA strand, protein will nestle in and recognize the nucleotides.
What part of the protein recognizes the nucleotides?
Relatively few structures are called DNA binding motifs.
What are DNA binding motifs?
DNA binding motifs are repeated structures on the protein that are able to bind. They are also called structural motifs. Very few of them exist, and they are used repetitive: helix-turn-helix motif and leucine zipper motif.
What are operons?
Groupings of genes that are for enzymes in one metabolic pathway. If an organism needs to engage in a process that turns A into B into C into D into E and needs and enzyme for each step, an operon will create all the enzymes simultaneously.
What does the trp operon do?
The trp operon makes enzymes to make tryptophan (an amino acid).
When is the trp operon on or off?
When tryptophan is absent, the trp operon will turn on to create it. When it is absent, the promoter is available and RNA polymerase binds to the promoter. Transcription then occurs. When tryptophan is present the trp operon will turn off and stop creating it. Transcription factor is available in the cell that acts as a repressor. 2 tryptophan molecules bind to the repressor to activate it. The repressor binds to the operator, and the promoter can no longer bind to the polymerase.
What happens when tryptophan is absent?
When tryptophan is absent, the promote is available and RNA polymerase binds to the promoter. Transcription then occurs.
What happens when tryptophan is present?
When tryptophan is present, the trp openon will turn off and stop creating it. Transcription factor is available in the cell that acts as a repressor. 2 tryptophan molecules bind to the repressor to acivate it. The repressor binds to the operator, and the promoter can no longer bind to the polymerase.
What does biosynthetic mean?
Biosynthetic means that it makes something.
Does a transcription factor act as a promoter or a represser with the trp operon?
The transcription factor acts as a repressor.
Is the promoter generally on or off with transcription factors and the trp operon?
The promoter is generally on, which means that it is a strong promoter. It can be turned on (by the previously mentioned repressor transcription factor.