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Flashcards in Exam 2 Deck (33):
1

Central Dogma of Molecular Biology

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

2

DNA

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

3

Base Stacking

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

4

Histones

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

5

Chromatin

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

6

Transcription

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”

7

mRNA

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

8

Promoter Region

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”

9

Enhancer

a specific DNA sequence necessary for transcription

10

Terminator

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

11

General Transcription Factors

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

12

polymerase

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”

13

mediator complex

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

14

triphosphate chain

provides the energy for transcription

15

Transcription-translation

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

16

mRNA modifications

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

17

exons

a sequence that is left intact in mRNA after RNA splicing

18

introns

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

19

alternative splicing

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”

20

tRNA

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”

21

codon

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

22

reading frame

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

23

Robert Hooke

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

24

Phospholipid bilayer

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

25

Fluid mosaic model

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

26

Transmembrane Proteins (integral and peripheral)

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

27

osmosis

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

28

isotonicity

cell at equilibrium and no osmosis possible

29

hypotonicity

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

30

hypertonicity

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

31

diffusion

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

32

aquaporins

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

33

passive diffusion

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