Exam 2

Question 1

Central Dogma of Molecular Biology

Answer 1

The flow of genetic information is from DNA to RNA to protein. DNA is transcribed to RNA, and RNA is translated to protien

Question 2

DNA

Answer 2

Deoxyribonucleic Acid (DNA): 
A polymer of nucleotides and forms a double helix

Question 3

Base Stacking

Answer 3

refers to the orientation of the structure of the nitrogenous bases, and this allows for the coiling properties of DNA
- Stabilizing interactions between bases in the same strand of DNA

Question 4

Histones

Answer 4

A complex of 8 proteins with a string of amino acids, forming a polypeptide chain *tail is important
- A protein found in all eukaryotes that interacts with DNA to form chromatin

Question 5

Chromatin

Answer 5

fiber; spiral of compacted histones wrapped in DNA
- A complex of DNA, RNA, and proteins that gives chromosomes their structure; chromatin fibers are either 30nm in diameter or, in a relaxed state, 10nm

Question 6

Transcription

Answer 6

during transcription, RNA polymerase reads a DNA sequence and produces a complementary, antiparallel strand of RNA.
“the process by which RNA is synthesized from a DNA template”

Question 7

mRNA

Answer 7

Messenger RNA, the RNA molecule that combines with a ribosome to direct protein synthesis, it carries the genetic “message” from the DNA to the ribosome

Question 8

Promoter Region

Answer 8

at front of a gene, on the DNA, where the polymerase will engage; it’s the region that initiates transcription of a particular gene, “ a regulatory region where RNA polymerase and associated proteins bind to the DNA duplex”

Question 9

Enhancer

Answer 9

a specific DNA sequence necessary for transcription

Question 10

Terminator

Answer 10

signals that the coding is finished, “a DNA sequence at which transcription stops and the transcript is released

Question 11

General Transcription Factors

Answer 11

bind to the promoter, and transcriptional activator proteins bind to enhancers

Question 12

polymerase

Answer 12

the enzyme that reads a strand of DNA and transcribes the corresponding RNA bases
*main enzyme responsible for transcription
“The enzyme that carries out polymerization of ribonucleoside triphosphates from a DNA template to produce an RNA transcript”

Question 13

mediator complex

Answer 13

“A complex of proteins that interacts with the Pol II complex, allows transcription to begin

Question 14

triphosphate chain

Answer 14

provides the energy for transcription

Question 15

Transcription-translation

Answer 15

Prokaryotes (one gene→ one product):
In prokaryotes, the primary transcript is immediately translated into protein, this is due to the lack of a nucleus in Pkryts

Eukaryotes:  Transcription and translation are separate; transcription occurs first in the nucleus, and then translation in the cytoplasm

Question 16

mRNA modifications

Answer 16

1. poly-A tail: protects the messenger RNA from enzymes when it leaves the nucleus (a stretch of adenines added to the 3’ end of the transcript)
2. 5’ cap: specialized hook for enzymes to transport mRNA (a 7-methylguanosine added to the 5’ end of the transcript)
3. Splicing: the excision of introns from the transcript bringing exons together

Question 17

exons

Answer 17

a sequence that is left intact in mRNA after RNA splicing

Question 18

introns

Answer 18

stay in the nucleus: a sequence that is excised from the primary transcript and degraded during RNA splicing

Question 19

alternative splicing

Answer 19

A process in which the primary transcripts from the same gene are spliced in different ways to yield different protein products; advantage is that one gene in the DNA can code for multiple protein products;
- “A process by which exons can be omitted or retained in an mRNA transcript”

Question 20

tRNA

Answer 20

transfer RNA, the molecule that brings the amino acids to the mRNA(reads the mRNA), “noncoding RNA that carries individual amino acids for use in translation”

Question 21

codon

Answer 21

“ a group of 3 adjacent nucleotides that specifies an amino acid in a protein or that terminates polypeptide synthesis”

Question 22

reading frame

Answer 22

following a start codon, a consecutive sequence of codons for amino acids

Question 23

Robert Hooke

Answer 23

: first person to describe a cell and created the early microscopes

Question 24

Phospholipid bilayer

Answer 24

have a hydrophilic head, made of a polar group, phosphate group, and a glycerol; and a hydrophobic tail made of 2 fatty acids

Question 25

Fluid mosaic model

Answer 25

idea that the phospholipid bilayer is fluid and a mosaic (mixture of 2 types of molecules: lipids and proteins)

Question 26

Transmembrane Proteins (integral and peripheral)

Answer 26

mediate exchanges across cell membrane to allow exchange of materials across membrane still to occur Integral: permanently associated with cell membrane Peripheral: can temporarily remove themselves, are easily separated

Question 27

osmosis

Answer 27

movement of water from higher concentration to lower concentration across a semi-permeable barrier

Question 28

isotonicity

Answer 28

cell at equilibrium and no osmosis possible

Question 29

hypotonicity

Answer 29

the cell is shrinking since water is leaving the cell. The solution has a higher solute concentration than the cell’s cytoplasm

Question 30

hypertonicity

Answer 30

the cell swells since water is entering. The cell’s cytoplasm has a higher solute concentration

Question 31

diffusion

Answer 31

movement of molecules from higher concentration to lower concentration until equilibrium reached

Question 32

aquaporins

Answer 32

class of transmembrane channel proteins; allows space for water to come and go through the membrane since cell membranes have non-polar centers, polar molecules can’t get through therefore it requires facilitated diffusion

Question 33

passive diffusion

Answer 33

molecules move directly through the lipid bilayer, and only works in the right direction