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Biology Exam 4 Flashcards

1
Q

Describe general amino acid and protein structure.

A

Proteins are a polymer of amino acids held together by a peptide bond.
Amino acid- central carbon with amino groupp , carboxyl group, proton, r group

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2
Q

What are the four levels of protein structure?

A

Primary 1°
Secondary 2°
Tertiary 3°
Quaternary 4°

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3
Q

Describe peptide bond.

A

covalent bond between two amino acids

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4
Q

Describe protein modification.

A

phosphorylation - changes charge; on/off switch for enzyme
glycolsylatoin - makes it slippery
lipidizatoin; adds lipid becomes part of a membrane; peripheral or lipid linked
Ubiquination: adds ubiquitin to protein to send to proteasome.

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5
Q

Describe role of proteasome and protein degradation in the cell.

A

Ubiquinated proteins are send to the proteasome for cleavage and recycling.

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6
Q

What are the nine main categories of proteins.

A
  1. Enzymes
  2. Regulatory Proteins
  3. Structural Proteins
  4. Motility Proteins
  5. Transport Proteins
  6. Receptor Proteins
  7. Hormonal Proteins
  8. Defensive Proteins
  9. Storage Proteins
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7
Q

Explain how environmental factors affect protein folding and function.

A

Changes in temperature, pH, and salt concentration disrupts the stabilizing bonds within protein structure. This causes the protein to unfold and become denatured.

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8
Q

Define and identify: coding/non coding, template/non template DNA strands.

A
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9
Q

Describe all function of RNA polymerase.

A
  1. Binds the promotor
  2. Melts hydrogen bonds (unwinds promotor)
  3. Unwinds DNA front of bubble
  4. Synthesizes RNA 5 -> 3
  5. Rewinds DNA at back of bubble
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10
Q

What are the three stages of transcription.

A
  1. Initiation
  2. Elongation
  3. Termination
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11
Q

Explain why wobble allow for 64 codons.

A

the third position does alternative base pairing allows it to have multiple codon targets

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12
Q

Explain role of signal sequences in protein targeting.

A

Signal sequences are located on the N-terminus of some proteins and enable those proteins to find their correct location

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13
Q

Describe primary protein structure.

A
  • a sequence of amino acids
  • synthesized and read from n-terminus to c-terminus
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14
Q

Describe secondary protein structure.

A
  • 3D arrangement of the primary sequence
  • alpha helix or beta helix
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15
Q

Describe tertiary protein structure.

A

3D arrangement of secondary structure
- Globular Proteins
- Fibrous Proteins
- Transmembrane Proteins

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16
Q

Describe quaternary protein structure.

A
  • 3D arrangement of polypeptides in a multi subunit protein complex (2 proteins interacting to be functional)
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17
Q

What is the function of enzymes?

A
  • Catalyze chemical reactions (make bond, break bond)
  • Bind substances and convert them into products
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18
Q

What is the function of regulatory proteins?

A
  • Bind enzymes and control their functions.
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19
Q

What is the function of structural proteins?

A

Structural support to cells and tissues

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20
Q

What is the function of motility proteins?

A
  • Interact with structural proteins to generate motion
  • Can move individual proteins, vesicles, organelles, chromosomes, or larger structures
  • Movement requires energy: often bind ATP
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21
Q

What is the function of transport proteins?

A
  • Control movement of small molecules across membranes
  • Always found in membranes
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22
Q

What is the function of receptor proteins?

A
  • Bind to signaling molecules (including molecules)
  • In membrane and cytosol
  • Bind to signal and pass it on
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23
Q

What is the function of hormonal proteins?

A
  • Chemical signals between cells in multicellular organisms
  • Circulate to distant cells
  • Bind cell surface receptors on target cells
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24
Q

What is the function of defensive proteins?

A
  • Target and neutralize harmful molecules
  • Ex: antibodies
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25
What is the function of storage proteins?
- Bind to and protect energy sources - Facilitate long-term storage of energy molecules
26
What is the shape of a fibrous protein?
Long and Narrow
27
What is the purpose of a fibrous protein?
structural
28
What is the amino acid sequence of a fibrous protein?
repetitive
29
What is the durability of a fibrous protein?
Less sensitive to changes in pH and temperature
30
What is an example of a fibrous protein?
Nuclear laming, collagen, fibrin, keratin
31
What is the solubility of a fibrous protein?
(Generally) insoluble in water
32
What is the shape of a globular protein?
Round/spherical
33
What is the purpose of a globular protein?
Functional
34
What is the amino acid sequence of a globular protein?
Irregular
35
What is the durability of a globular protein?
More sensitive to changes in pH and temperature
36
What is an example of a globular protein?
Histones, enzymes, hemoglobin, insulin
37
What is the solubility of a globular protein?
(Generally) soluble in water
38
What is the structure of an alpha helix?
- 3.6 amino acid per turn - stabilized by hydrogen bonds between every 4th amnio acid - R-groups extend outward uninterrupted sequence of amino acids
39
What is the structure of a beta sheet?
- stabilized by hydrogen bonds in polypeptide backbone - bonds form between aligned strands - parallel or anti parallel - Strands in sheet are separated by loops that allow chain to curve around
40
What determines protein shape?
amino acid sequence
41
Are non polar amino acids hydrophobic or hydrophilic?
hydrophobic
42
Are polar amino acids hydrophobic or hydrophilic?
hydrophilic
43
Are ionic amino acids hydrophobic or hydrophilic?
hydrophilic
44
What determines protein function?
Shape
45
How many amino acids are in an average protein?
300-500
46
What hold amino acids together?
peptide bonds
47
Are most peptide bonds in the trans or Cis configuration?
trans
48
Is protein structure regular or predictable?
no
49
What is a beta barrel?
A large enough beta sheet that can fold into a beta barrel
50
Characteristics of a globular protein?
- condensed, rounded - hydrophobic amino acids inside, hydrophilic outside
51
Characteristics of fibrous proteins?
- rich in a- helices and b-sheets - resistant to mechanical force (STRONG)
52
Characteristics of transmembrane proteins?
- span membrane - transmit info across membrane - Ex: signaling receptors
53
What is a domain?
subsection of a protein with a particular function (section of protein)
54
Unfolded 1degree structure
peptide
55
folded functional 3degree structure
protein
56
What is ubiquination?
bonding of an ubiquitin protein to a protein which acts as a signal to destroy that protein
57
What is the function of phosphorylation for a protein?
on/off with for an enzymes; adds phosphate group to protein
58
What is the function of glycosylation for a protein?
addition of a sugar to the protein; makes cell slippery so they can move past each other
59
What is the function of farnelyaition for a protein?
adds a lipid molecule to the protein
60
What factors change protein shape?
- Environmental change - Covalent modification - Non covalent modification
61
What maintains the circadian clock?
protein degradation
62
What occurs in transcription initiation?
- RNA polymerase binds to the promotor sequence - RNA pol melts promotor DNA - RNA pol begins synthesis without a primer
63
How does RNA pol find a promotor sequence?
looks for a particular sequence
64
What occurs in transcription elongation?
- RNA pol makes an RNA strand complementary to the template DNA in a 5 to 3 direction - only one strand of DNA gets copied
65
What occurs in transcription termination?
- RNA pol reaches termination sequence - RNA pol pauses - mRNA folds up into a hair-pin loop or Rho protein binds - RNA pol release DNA and RNA
66
What are some differences between eukaryote and prokaryote RNA?
- Eukaryote RNA must get processed to get out of the nuclear pore - Eukaryote mRNAs separated from ribosomes by nuclear membranes - Prok ribosomes bind mRNA while RNA pol is still working.
67
What is translated to a protein?
mRNA
68
What carry out translation?
Ribosomes
69
What is a codon?
a set of 3 nucleotides
70
What does each codon indicate?
a specific amino acid that should be added to the protein
71
What is the start codon what what does it tell the ribosome?
Start codon = AUG It tells the ribosome where it should start adding amino acids
72
What are the stop codons?
UAG, UAA, UGA
73
Does the stop codon code for an amino acid?
no
74
What is a ribosome?
- a large structure composed of both protein and ribosomal RNA (rRNA)
75
What is the function of a ribosome?
binds the messenger RNA and organizes translation
76
What does tRNA do?
- Delivers amino acids to ribosomes - binds to an amino acid on ones side - has an anticodon on the other side: a 3 nucleotide sequence that is complementary to the mRNA codon
77
How are amino acids connected to the tRNA?
- amnoacyl tRNA synthetase uses ATP energy to couple amino acids to the tRNA - The bond that hold the amino acid and the tRNA together is used as energy later to create the peptide bond in the growing protein chain
78
What term reflects the energy of tRNAs coupled to amino acids?
charged
79
What are the stages of Translation?
- Initiation - Elongation 1 - Elongation II - Elongation III - Termination
80
What are the three binding sites in a ribosome for tRNA?
1) a (aminoacyl) 2) p (polypeptide) 3) e (exit)
81
What occurs during translation initiation?
- Ribosome attaches to mRNA - Ribosome moves down until it find the "START" codon (AUG) - The first tRNA binds to the "P"site of the ribosome
82
What occurs during translation elongation I?
- The tRNA that has the next correct anticodon can come into the "a" site. - From now on, all new tRNA enter "A" site
83
What occurs during translation elongation II?
- The amino acid on the "a" tRNA becomes linked to the polypeptide chain in the "P" position - the enzyme peptide transferase makes a peptide bond between the amino acids. - The polypeptide chain then disconnects from the "P" tRNA and is connected to the "A" tRNA
84
What occurs during translation elongation III?
- The ribosome moves down the mRNA - The tRNA with the polypeptide chain shits to the "P" position - The tRNA that unlinked its amino acid moves to the "E" (exit) site
85
What occurs during translation termination?
- a stop codon is encountered - stop codons do not bind tRNA molecules - stop codons attract proteins called release factors - fit in the "a" site - the polypeptide chain is cleaved off the tRNA in the "P" site. - Everything can be recycled for another round of translation
85
What is a signal sequence?
n- terminus AA are signal for protein destination often cleaved off after reaching destination
86
What is the function of mRNA?
transcribes the genetic code from DNA into a form that can be read and used to make proteins
87
What enzyme makes the peptide bond between amino acids in elongation II?
peptide transferase

Biology (6 decks)

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