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Biology 243 Lab Exam Flashcards Quizlet

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Mathematics Fundamentals (MATH 020)

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Istituto di Istruzione Superiore Mariano IV d'Arborea

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Biology 243 Lab Exam

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Terms in this set (121)

DNA replication

process of copying the DNA within a cell, during replication each DNA molecule in the cell is copied to make 2 identical molecules. Occurs as part of the cell cycle.

What is the primary role of DNA?

provide instructions for how and when to build proteins and other molecules. Cell makes precise proteins that it needs at the moment it needs them.

A double stranded molecule of DNA is called what?

chromosome

. What are chemical components of a deoxyribonucleotide?

  1. A five-carbon deoxyribose sugar
  2. One of four nitrogenous bases (adenine, thymine, guanine, or cytosine) (bound to 1')
  3. At least one phosphate group (there can be up to 3 bound to each other in a row) bound to 5'

Study sets, textbooks, questions

Biology 243 Lab Exam

How are deoxyribonucleotides joined together to make DNA?

Through the formation of a type of covalent bond called a 3',5'-phosphodiester bond (linkage) catalyzed by the enzyme DNA Polymerase before mitosis or meiosis:

  1. A phosphodiester bond forms between the phosphate group on the 5' carbon of an INCOMING deoxyribonucleotide and the hydroxyl group on the 3' carbon of the deoxyribose from the last monomer of the growing DNA chain.
  2. If there's more than one phosphate on the deoxyribonucleotide, then all except one phosphate will leave so that it can join with the oxygen on the hydroxyl group already on the chain (after the hydrogen takes its leave, of course)
  3. The phosphate attached to the 5' carbon always reacts with the hydroxyl attached to the 3' carbon of the deoxyribose. This is how DNA Polymerase arranges them. The hydroxyl group on the 3' carbon is the only place for another deoxyribonucleotide to join.

DNA is a polymer which is a large subunit made up of?

Monomers which are nucleotides.

How are polymers made? through polymerization, performed by enzymes called polymerases.

How do DNA strands form the antiparallel double helix?

DNA Polymerase is responsible for it. This is what pairs the bases with complementary bases, so the 5' end of the template strand ends up being near the 3' end of the complementary strand.

Biology 243 Lab Exam

Nucleotide prefixes? Maybe on the exam?

A chain with 1 nucleotide is called a mononucleotide A chain with 2 nucleotides is called a dinucleotide. A chain with 3 nucleotides is called a trinucleotide. A chain with 5 nucleotides is called a pentanucleotide. A chain with 6 nucleotides is called a hexanucleotide. A chain with 7 nucleotides is called a heptanucleotide. ..........

What are Nitrogenous Bases and how are they bonded?

The bases of DNA that contain carbon, hydrogen, oxygen, and nitrogen which include: adenine, thymine, guanine, and cytosine. These are covalently bound to carbon 1' of the deoxyribose, but take part in stable base-pairing with their complementary base via very specific hydrogen bonds (eg. between A and T, there're two hydrogen bonds, while between G and C, there are three)

What is the difference between a purine and a pyrimidine base?

Purines like adenine and guanine are bigger and two-ringed while pyrimidines like thymine and cytosine are smaller and single-ringed.

What are histones?

They are positively charged protein molecules around which DNA is tightly coiled into chromatin. The histones allow DNA to be packaged compactly to allow for movement during cell division.

Biology 243 Lab Exam

Linear vs Circular DNA

Eukaryotic cells have double stranded linear DNA. Prokaryotic cells and mitochondria and chloroplasts have single stranded circular DNA that also runs antiparallel and is replicated the same way as linear DNA.

What is PCR used for?

to rapidly amplify, or copy a specific target region of DNA.

What is not needed in PCR? In PCR what are primers made of? Where do primers bind on PCR?

Helicase Single-stranded DNA The ends of the region to amplify

How to select a good primer for PCR

  1. Pick the region of DNA to amplify
  2. Find the complementary sequence to the region you wish to amplify
  3. Make sure the primer sequence is written in the correct orientation (5'-3')

After 2 cycles of PCR how many double stranded DNA molecules do you have? How about after 3?

4, & 8

If you forgot to add dNTP's to your PCR what would happen? If the temp was always set to -95 what would happen?

DNA polymerase could not extend the primers. Primers would be unable to anneal

Why is DNA pol 1 not used in PCR?

There are no RNA primers to remove

Biology 243 Lab Exam

When are LacZ and LacY genes expressed?

Bacterial cells conditionally express the lacZ and lacY genes, so their proteins are only produced when lactose is present.

What does the LacZ protein do?

cuts lactose into 2 smaller sugars

What does the LacY protein do?

transporter that moves lactose into cells.

How does repressor bind to lactose?

lactose bind to receptor protein, thus changing the shape of it.

Where on DNA can the repressor bind?

ONLY onto the operator

Describe how to transform bacteria with a plasmid

  1. Make a mixture of CaCl2 and the plasmid
  2. Put the bacteria into a plate with lysogenic broth and arabinose at the very least
  3. Heat shock it. Hot, cold, room temp.
  4. Set aside for incubation. Wait

Biology 243 Lab Exam

Describe aseptic technique

This sterile technique ensures that you don't contaminate yourself or your specimens:

  1. Wear a clean lab coat, buttoned up, and sleeves rolled down. Also, don't show skin and tie hair back.
  2. Free the bench space of anything you won't be using and spray the bench with disinfectant before and after the lab.
  3. Wash your hands thoroughly before and after the lab

What is a plasmid?

A small ring of DNA that carries accessory genes independent from those of the bacterial chromosome. Bacteria usually have one or more of these. They contain genes for one or more traits that are beneficial but not essential for survival

What is bacterial Transformation?

process in which one strain of bacteria is changed (both genotype and phenotype) by a gene or genes from another strain of bacteria.

what is the Promoter?

specific region of a gene where RNA polymerase can bind and begin transcription

what is the Operator?

Region of DNA that controls RNA polymerase's access to a set of genes with related functions

Biology 243 Lab Exam

Describe translation

  1. Initiation: the ribosome attaches to the mRNA strand, reading the first codon (usually AUG). Then the specialized tRNA molecule that carries methionine recognizes the codon and binds to it. (and waits for the next amino acid to be carried in)
  2. Elongation: as the ribosome shifts to the next codon, there's a brief moment when there are two tRNA molecules bound to the mRNA strand before the first amino acid lets go of its tRNA molecule (which also lets go of the mRNA strand) and binds to the second amino acid attached to its tRNA molecule. This continues, and as the string of amino acids gets longer, it emerges from the top of the ribosome.
  3. Termination: elongation continues until the ribosome reaches a stop codon. Then, the ribosome lets go of the mRNA strand and sets the string of amino acids free

Why can mutations be both silent and cause effects on genes?

Because of their random nature. Because more than one sequence codes for most amino acids, it's entirely possible that a point mutation will just make the codon code for the same amino acid. However, it's just as likely that it won't do that, and it could cause some damage in terms of protein structure

what is a Synonymous Mutation (silent mutation)?

A base pair substitution that does not change the amino acid that a codon normally produces

Biology 243 Lab Exam

what is a Nonsense Mutation?

A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein

what is a Nonsynonymous Mutation?

A mutation in a gene that changes the amino acid sequence of the protein that gene encodes (different amino acid)

which mutation is most selected against and why?

nonsense mutations. Because when DNA experiences a nonsense mutation the sense codon is changed to a stop codon which results in the polypeptide being terminated prematurely. This can result in a polypeptide that is only partially functional

what is Mitosis?

The process by which one copy of each chromosome is given to each daughter cell with a full complement of genetic material identical to the parent cell's. In the event that a daughter cell is given more or less chromosomes than it should have, it usually ends up dying, or in rare cases, live to act abnormally.

Describe interphase

Period of the cell cycle between cell divisions in which the cell carries out its metabolic functions and prepares for its next division. G1, S phase (DNA replication happens here), G2. The cell spends about 90% of its life in here

Biology 243 Lab Exam

What are the effects of caffeine on mitosis?

caffeine has the greatest impact on anaphase and telophase phase, cells treated with small amounts of caffeine move through most of the mitotic events as normal. But when the cell reaches telophase the process to form the cell plate does not occur normally, this is due to the failure of vesicles to fuse together. cells with caffeine have partial cell plates in cytokinesis. Caffeine lengthens the s-phase of the cell cycle, affecting time it takes for the cell to reach the other stages of mitosis.

what is the p-value?

probability that the difference you're looking at is due to chance alone. This is the value that tells you if the difference is significant.. p ≤ 5%

Describe how to interpret the χ^2 value

  1. Determine an acceptable p-value and compare it to your χ^2 calculations
  2. Find the degrees of freedom
  3. If χ^2 > p, then the difference is significant (due to something other than chance) so we reject the null hypothesis. If χ^2 < p The difference is non- significant

What are degrees of freedom and what is the formula for the chi square df?

One less than the number of categories (n - 1). Another way of expressing variability of your sample.

Biology 243 Lab Exam

Describe how to prepare a wet mount on a microscope

  1. Place your specimen in a drop of distilled water on a clean slide.
  2. Add a coverslip with one side touching the water and gently lower the other side, making sure there are no air bubbles.
  3. If the coverslip is floating on the slide, you've added too much liquid. Take a Kimwipe and press it to the side of your preparation.
  4. If there are dry areas under your coverslip, touch an eye dropper with water to the edge of the cover slip and let osmosis do the rest.

Label the parts of a microscope

look at diagram

What is the objective of a cover slip?

It protects the objective lens, flattens the preparation, and keeps the specimen from drying out

Describe anaphase 1

homologous chromosomes separate. The nuclear envelope reforms and nucleoli reappear. The chromosomes coil up, the nuclear membrane begins to disintegrate, and the centrosomes begin moving apart. Spindle fibers form and sister chromatids align to the equator of the cell.

Biology 243 Lab Exam

what is the Segregation of Alleles?

As chromosomes separate into different gametes during meiosis, the two different alleles for a particular gene also segregate so that each gamete acquires one of the two alleles

what is independent assortment?

random distribution of the pairs of genes on different chromosomes to the gametes

what is the gene locus? a specific location of a gene along the chromosome

How would you recognize a monohybrid cross?

parents would both be homozygous for different alleles (they'd show different phenotypes) and all their offspring would be heterozygous.

Homozygous dominant vs. homozygous recessive

both terms indicate that the zygote inherited the same allele from each parent, but dominant refers to the "normal" one (bc it overpowers the recessive in terms of phenotype AA). For the recessive phenotype to be shown, the zygote must be homozygous recessive (aa)

What does heterozygous mean?

When the two alleles inherited by the zygote are different. The phenotype is that of the dominant allele (Aa)

What does F1 stand for? first filial generation

Biology 243 Lab Exam

What are the cell growth periods called?

G1 and G2 phases

Which phase does DNA replication occur?

S phase of interphase

When does the cell replicate DNA?

before mitosis

How are sister chromatids held together?

cohesin proteins

What is the spindle assembly checkpoint?

safeguard against aneuploidy. at the end of metaphase a cell will not enter anaphase until all chromosomes are connected to microtubules from both poles and positioned at the midline. This checkpoint is enforced by signalling proteins.

Describe binary fission

Cell division (asexual reproduction) in prokaryotes that replicates the cell's chromosomes, segregates the copied DNA, and splits the parent cell's cytoplasm

Describe what happens outside of the nucleus during prophase

Centrosomes move to opposite parts of the cell and begin building the mitotic spindle (which makes the sister chromatids move to opposite poles during anaphase)

Biology 243 Lab Exam

Differences between mitosis and meiosis

  1. Prophase of mitosis doesn't have the chromosomes form tetrads.
  2. Meiosis results in new combinations of genes while mitosis makes copies.
  3. Meiosis involves two rounds of cell division while mitosis involves one. Note that meiosis II is more similar to mitosis than to meiosis I.
  4. The presence of an interkinesis stage in which no DNA replication happens

How would you predict the patterns of inheritance and what relevant data would you need?

You would need the genotype of the parental generation, and the genotype of the organism crossed with the F1 generation

Why can bacteria be used to observe evolution?

Because they have a shorter generation time, which visibly speeds up this immensely slow process enough that it can be tracked

How does salinity influence the growth and survival of organisms?

Through the effects of salt on osmotic balance as well as direct effects on proteins

Biology 243 Lab Exam

what is the relationship between the distance across the dish and the salinity gradient? How do you find the conversion factor for this relationship?

The distance across the dish and the salinity gradient (sodium ion concentration) are directly proportional (linear relationship). To find the conversion factor, divide the maximum saline concentration by the diameter of the plate

What is the formula for standard error of the mean (SEM)?

√[ Σ(x - xi)^2 / n(n-1) ] where n = the number of things you have x = your value for a specific trial xi = your sample mean (all the results added up and then divided by n

What is the difference between statistical significance and biological significance?

Statistical significance depends purely on numbers while biological significance depends on context (how big is SEM? Will this make a difference in real life? How variable is the data? What are the sources of error? How sensitive to change of the environment are the results? Can they be replicated?)

What is biological significance?

difference in treatment groups that has noticeable, not simply mathematical difference (eg. would a patient noticeably benefit from a treatment shown to be significantly different from other treatments?)

How many colonies should be on the LB/-pGLO plate? And should the bacteria fluoresce?

too many to count, and no

Biology 243 Lab Exam

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Biology 243 Lab Exam Flashcards Quizlet

Course: Mathematics Fundamentals (MATH 020)

999+ Documents
Students shared 3475 documents in this course

University: Istituto di Istruzione Superiore Mariano IV d'Arborea

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Profi
Biology 243 Lab Exam
9 studiers in the last hour
Terms in this set (121)
DNA replication
process of copying the DNA within a cell, during
replication each DNA molecule in the cell is copied
to make 2 identical molecules. Occurs as part of the
cell cycle.
What is the primary role of
DNA?
provide instructions for how and when to build
proteins and other molecules. Cell makes precise
proteins that it needs at the moment it needs them.
A double stranded molecule of
DNA is called what?
chromosome
. What are chemical
components of a
deoxyribonucleotide?
1. A five-carbon deoxyribose sugar
2. One of four nitrogenous bases (adenine, thymine,
guanine, or cytosine) (bound to 1')
3. At least one phosphate group (there can be up to
3 bound to each other in a row) bound to 5'
Study sets, textbooks, questions

Students also viewed

Related documents