BIOCHEM 420 Chapter Notes - Chapter 2: Molecular Partners, Intermolecular Force, Dimensionless Quantity

10 views6 pages

turquoisedonkey428

2 Oct 2020

School

UMASS-Amherst

Department

Biochemistry & Molecular Bio.

Course

BIOCHEM 420

Professor

Elizabeth Mearls

For unlimited access to Textbook Notes, a Class+ subscription is required.

Document Summary

Chapter 2 - the chemical foundation of life: weak. Interactions in an aqueous environment: 1 the importance of non covalent interactions in biochemistry. The linear sequence of the nucleotide residues in a strand of dna is maintained by covalent bonds. Dna is stabilized by non covalent interactions between different parts of the molecule. The covalent bonds most important in biology (c - c and c - h) have bond energies in the range of 150 - 400 k jimol. Biologically important non covalent bonds are roughly 10 to 100 times weaker (cid:8869) their weakness is what makes noncovalent bonds - so essential. Electrostatic : all depend on the forces that electrical charges exert on one another. Also known as ionic bonds or salt bridges. T2 (cid:8869) k is a constant whose value depends on the units used. In a cell , charges are always surrounded , or separated , by water or other molecules.

Related Questions

Second messengers play an important role in cellcommunication.

Which of the following best describes their role?

		None
		integrate, amplify and distribute messages throughout thecell
		Release messages to other cells?
		Receive information at the cell surface

What is true of disulfide bonds?

	a.	They often occur in the cytosol
	b.	They are a noncovalent bond
	c.	They are formed enzymatically in the ER
	d.	They act as reducing agents
	e.	they increase protein flexibility

Which of the following is NOT an example of a cell communicationmolecule?

		nucleases
		nitric oxide
		hormones
		kinases

What is true of binding pockets?

	a.	They only occur in the membrane
	b.	They occur in unfolded proteins
	c.	They contain electrostatic interactions
	d.	They contain variable amino acids
	e.

What is true of cell signaling?

	a.	Extracellular signals transduced by rectors always alter cellbehavior very quickly
	b.	Some cells require cell signals just to survive
	c.	Cell signals can be interpreted differently by differentcells
	d.	B and C only
	e.	All of the above (A, B and C)

Histone tails can be modified to change the shape and"tightness" of the nucleosomes. Acetylated histones result in whicheffect?

		Open DNA
		increased transcription
		closed DNA
		decreased transcription
		1+2
		1+4
		3+4
		2+3

Shifting the two bound tRNA from the A and P sites to the E andP sites of the ribosome involves:

	a.	The movement of the small ribosome subunit down the mRNAchain
	b.	The degradation of the A site on ribosome
	c.	The synthesis of the E site on the ribosome
	d.	The movement of the large subunit relative to the smallsubunit
	e.	All of the above

Intracellular signaling pathways are awesome! What is the onething they can NOT do?

	a.	relay the signal, to spread it through the cell
	b.	nothing, they can communicate any cellular need
	c.	distribute the signal to more than one effector protein
	d.	integrate the signal from more than one cellular pathway
	e.	Amplify the signal received, making the signal stronger

Specificity of protein/protein and protein/DNA binding isdetermined by what?

		Non-covalent bonds
		Hydrophobic interactions
		Covalent bonds
		shape of the binding site
		all of the above
		none of the above
		1,2,3
		1,2,4
		1,3,4

The coiling structure of the DNA into chromosomes is achieved bywhat?

		alpha helix
		beta pleated sheets
		chaperone proteins
		DNA/Protein complexing

Which regions (s) of the DNA are found in the final protein?

	a.	poly-A tail
	b.	A and B
	c.	Exons
	d.	UTRs
	e.	Introns

Metabolic processes can be turned "on" and "off" by chemicalmodifcation.

Which chemical modification do we associate with changing theactivity of an enzyme in a transient/non-permanent manner?

		Phosphorylation
		Ubiquitination
		Methylation
		Acetylation

DNA hybridization involves attaching a florescent dye towhat?

	a.	Antibody
	b.	Nuclear stain
	c.	Probe DNA
	d.	tRNA
	e.	rRNA

sapphirecrocodile239

__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location.

Lysosomes

Endosomes

Peroxisomes

Nucleosomes

Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies?

rapid rate of reproduction

all of the above

ability to grow under controlled conditions

amenability to genetic manipulation

By definition, prokaryotic cells do not possess __________.

ribosomes.

a nucleus.

membrane bilayers.

replication machinery.

Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell. Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the __________ of light.

intensity

absorption

wavelength

filtering

Choose the phrase that best completes this sentence: Microtubules ____________ and are required to pull duplicated chromosomes to opposite poles of dividing cells.

generate contractile forces

can rapidly reorganize

are found in especially large numbers in muscle cells

are intermediate in thickness

Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton?

cell division

cell motility

vesicle transport

membrane support

DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA but not true of RNA?

It contains thymine.

It has 5'-to-3' directionality.

It is single-stranded.

It contains uracil.

Double covalent bonds are both shorter and stronger than single covalent bonds, but they also limit the geometry of the molecule because they ____________________.

prevent additional bonds from being formed with the bonded atoms.

limit the rotation of the bonded atoms.

create a new arrangement of electron shells.

change the reactivity of the bonded atoms.

Drosophila melanogaster is a/an __________. This type of animal is the most abundant of all animal species, making it an appropriate choice as an experimental model.

mammal

amphibian

bird

insect

10.

If the isotope 32S has 16 protons and 16 neutrons, how many protons, neutrons, and electrons will the isotope 35S have, respectively?

16, 19, 17

16, 19, 15

16, 19, 16

16, 20, 15

11.

Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following can be described as the smallest living unit?

cell

organelle

protein

DNA

12.

Macromolecules in the cell can often interact transiently as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in determining whether the interaction will be transient or stable?

the concentration of each molecule

the size of each molecule

surface complementarity between molecules

the rate of synthesis

13.

Many of the mechanisms that cells use for maintenance and reproduction were first studied at the molecular level in bacteria. Which bacterial species had a central role in advancing the field of molecular biology?

E. coli

S. pombe

C. elegans

D. melanogaster

14.

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets. What is the lipid most commonly found in these droplets?

cholesterol

isoprene

triacylglycerol

palmitic acid

15.

Mitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are __________________.

anaerobes.

viruses.

parasites.

endosymbionts.

16.

Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. Which answer below indicates a correct pairing of material âburnedâ and the form of energy produced during cellular respiration?

17.

Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds?

1. Characters that show a continuous range of variation, such as height and eye color, usually are controlled:

a.	by a single gene with two alleles that are codominant.

b.	by many genes with an additive effect.

c.	by epistatic interactions between two genes.

d.	mainly by the environment, with only a small genetic component.

2. In humans, red-green colorblindness is inherited as a sex-linked recessive trait. In order for a woman to be red-green colorblind, which of the following statements must be true.

a.	Her mother must be red-green colorblind.

b.	All of her brothers must be red-green colorblind.

c.	Her father must be red-green colorblind.

d.	All of the above statements must be true if a woman is red-green colorblind.

3. The x-ray crystallography data collected by Rosalind Franklin suggested to Watson and Crick that the:

a.	structure of DNA is a double helix.

b.	two strands of the DNA molecule are joined by hydrogen bonds between the bases.

c.	four bases within DNA pair in a specific way.

d.	two strands of the DNA molecule are joined by covalent bonds between the bases.

4. In the genetic code, _________ one amino acid.

a.	one nucleotide specifies

b.	two nucleotides specify

c.	three nucleotides specify

d.	four nucleotides specify

5. During Meiosis I, a homologous pair of chromosomes may not separate, resulting in daughter cells that have extra chromosomes or are missing chromosomes. This can lead to genetic disorders, including Down Syndrome. This phenomenon is called:

a.	independent assortment.

b.	nondisjunction.

c.	segregation.

d.	crossing over.

6. You are a human geneticist studying the incidence of retinitis pigmentosa in the residents of Tristan de Cunha, a group of small islands in the middle of the southern Atlantic Ocean. The allele for retinitis pigmentosa, which causes a form of blindness, is inherited as an autosomal recessive. You have determined that the frequency of this allele (r) in the population is 0.4 (40%). Using the principles of the Hardy-Weinberg rule, you would estimate the frequency of individuals who are heterozygous for this allele (Rr) in the population to be:

a.	0.16 (16%)

b.	0.24 (24%)

c.	0.36 (36%)

d.	0.48 (48%)

7. Natural selection acts at the level of the:

a.	phenotype.

gene.

c.	population.

d.	nucleotide.

8. You are working with pea plants, trying to recreate the experiments that Mendel performed. You are doing a dihybrid cross with a plant that is heterozygous for both seed shape and seed color, with the genotype RrYy. Which allelic combinations would you expect to find in the gametes produced by this plant?

a.	This plant would produce only RY and ry gametes.

b.	This plant would produce only RrYy gametes.

c.	This plant would produce RY, Ry, rY, and ry gametes.

d.	You cannot determine which gametes this plant can produce without knowing the genotypes of its parents.

9. Biochemist Erwin Chargaff found that in DNA there is a special relationship between the four bases that we now call Chargaff's rule. His observation was that, in an organism's genome the:

a.	percentage of A nucleotides = the percentage of T nucleotides, and the percentage of C nucleotides = the percentage of G nucleotides.

b.	four bases all occur in an equal frequency (25%) within each organism.

c.	percentage of A nucleotides = the percentage of G nucleotides, and the percentage of C nucleotides = the percentage of T nucleotides.

d.	genetic material is composed of proteins, not DNA.

10. During DNA replication:

a.	each strand of the double helix acts as a template for the synthesis of a new strand.

b.	the enzyme DNA polymerase adds nucleotides to the strand being synthesized.

c.	the bases A,C,G and T are required.

d.	All of the above are true of DNA replication.

11. During translation, amino acids are joined by peptide bonds to make polypeptides. The formation of these peptide bonds is catalyzed by:

12. If an allele (R) at a gene with two alleles shows complete dominance, individuals with the genotypes ______ will have the same phenotype.

a.	RR and rr.

RR and Rr

Rr and rr

d.	Each of the three possible genotypes will have a different phenotype.

mauvefox570

BIOCHEM 420 Chapter Notes - Chapter 2: Molecular Partners, Intermolecular Force, Dimensionless Quantity

Document Summary

Get access

Related textbook solutions

Molecular Cell Biology

Biology: Science for Life with Physiology

Concepts of Biology

Biology

Essentials of Biology

Related Documents

BIOCHEM 420 Lecture Notes - Lecture 8: Conformational Entropy, Non-Covalent Interactions, Globular Protein

BCHM-3050 Lecture Notes - Lecture 1: Non-Covalent Interactions, Molecular Symmetry, Covalent Bond

BIOC 299 Lecture Notes - Lecture 2: Sodium Hydroxide, Hydrophile, Acid Dissociation Constant

Related Questions