Gene Expression and Protein Synthesis (1) Flashcards
Exam 1
1
Q
True or False:
The nucleus is the smallest organelle.
A
False:
The nucleus is the largest organelle
2
Q
What is the function of the nucleus?
A
Stores genetic information
3
Q
What is the function of the nucleolus?
A
formation of ribosomes (using RNA)
4
Q
What is the nuclear envelope?
A
double membrane around the nucleus
5
Q
What are nuclear pores?
A
regulate passage of substances
-hold membrane together
6
Q
What is the nucleoplasm?
A
material in nucleus
7
Q
What is chromatin?
A
- Diffuse DNA (some RNA)
- -prior to division –> converts to chromosome
8
Q
What is a gene traditionally?
A
a segment of DNA that codes for a particular protein
- codes first for mRNA –> protein
- -TONS of PROTEINS
- -20,000 genes
9
Q
What is the current definition of a gene?
A
An information-containing segment of DNA that codes for the production of a molecule of RNA that plays a role in synthesizing one or more proteins
10
Q
Amino Acid sequence of a protein is determined by the ____ sequence in the DNA
A
nucleotide
11
Q
How many separate human DNA molecules (chromosomes) are there?
How many pairs does that make and where do they come from?
A
- 46 separate
- 23 pairs
- –set from each parent
12
Q
Genome Definition
A
all the genes in 23 pairs
13
Q
What is genomics?
A
study of the whole genome and how its genes and noncoding DNA interact to affect structure and function of the whole organism
14
Q
A single gene can code for ___ ____ proteins
A
- many
- different
15
Q
The function and regulation of most genes is ___
A
unknown
16
Q
True or False:
All humans are at least 99.9% genetically identical
A
True
17
Q
Genetic Code Definition
A
a system that enables these four nucleotides to code for amino acid sequences of all proteins
18
Q
Proteome Definition
A
Specific proteins expressed in a given cell at a particular time
19
Q
True or False:
DNA language is the same as protein language
A
false
DNA language is different than protein language
20
Q
Codon Definition
A
three letter (nucleotide) unit of mRNA
- -codes for single amino acids
- -61 triplets (3 are stop codons)
21
Q
What is a stop codons and a start codon?
A
stop codons: signal “end of message”
start codon: (methionine [AUG]) begins the amino acid sequence
22
Q
From ___ to ___ to ___
A
DNA
RNA
Protein
23
Q
Molecular Genetics Definition
A
how genes control the building of specific proteins
24
Q
Gene Expression Definition
A
protein codes for functions in the cell
25
What are the two steps of gene expression?
1. Transcription
| 2. Translation
26
Cells differ in structure and function because....
- different proteins do different jobs
| - only certain genes are expressed
27
Gene expression is controlled in the ___ which leads to...
- Cell
| - specialization of cells in tissue
28
What are the three types of RNA?
- Messenger RNA (mRNA) (pre-mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
29
Which RNA are produced in the nucleus?
mRNA and tRNA
30
Which RNA are produced in the nucleolus?
rRNA
31
What is the function of mRNA?
- transcription
| - translation
32
What is the function of tRNA?
-transfers amino acids to ribosomes
33
What is the function of rRNA?
component of ribosome that joins the large and small subunits
34
What is made when a gene is activated during protein synthesis?
mRNA
35
What is the process of protein synthesis?
DNA --> mRNA --> Protein
- Transcription: DNA -->mRNA
- Translation mRNA --> Protien
36
Where does transcription take place?
nucleus
37
Where does translation take place?
cytoplasm
38
True or False:
| Transcription is the creation of mRNA from DNA
True
39
Introns...
stay inside the nucleus
40
Exons...
exit the nucleus
41
Alternative Splicing Definition
variations in the way axons are spliced
| --allows for a variety of proteins to be made from one gene
42
Ribosomes are located...
- outside the nucleus
- rough ER
- nuclear envelope
43
What is the function of ribosomes?
- read mRNA- build the protein
| - facilitate pairings between codons and anticodons of tRNA
44
What happens at the p-binding site?
amino acid chain is growing
45
what happens at the a-binding site?
newly arrived tRNA comes in
46
what happens at the e-binding site?
exit
47
What are the three steps of translation?
- initiation
- elongation
- termination
48
What happens during initiation?
- A small ribosomal subunit binds to mRNA; an initiator tRNA pairs with the mRNA start codon: AUG
- The large ribosomal subunit completes the ribosome. Initiator tRNA occupies the P site. The A site is ready for the next tRNA
49
What happens during elongation?
-ribosome slides to read next codon
-releases initiator tRNA (now at E site)
-next tRNA (anticodon) binds at the A site
-peptide bond form between growing amino acid chain
(process repeats until stop codon reached)
50
What happens during termination?
- The ribosome comes to a stop codon on the mRNA. A release factor binds to the site
- The release factor hydrolyzes the bond between the last tRNA at the P site and the polypeptide, releasing them. The ribosomal subunit dissociate.
51
What happens during translation?
- some proteins packaged others exported
- proteins headed for secretion are made on ribosomes on the rough ER
- --newly made protein is threaded into rough ER
- -----modified and packaged into a transport vesicle
52
Chaperone Protein Definition
- old proteins that are designed to help primary structure to fold into its proper form
- prevents improper association
53
What do stress proteins or heat-shocked proteins do?
-help damaged proteins fold back to functional form
54
How does protein processing and secretion work?
To work- primary structure must fold into precise secondary/ tertiary structures
55
What happens when translation is finished?
primary structure and amino acid sequence is formed
56
How are proteins to be used in the cytosol made?
Made by free ribosomes in cytosol
57
Where are proteins destined for packaging into lysosome for secretion from the cell assembled?
Assembled in the rough ER/ Golgi complex
58
What is going on inside the ER?
a complex system of channels (cisternae) enclosed by a membrane
59
Rough ER Definition
Parallel, flattened sacs
- -continuous with outer membrane of the nuclear envelope
- -studded with ribosomes
- ---produces phospholipids/proteins that go to the cell membrane
60
What does the rough ER form?
forms transport vesicles
61
Where do transport vesicles go for further modification?
- golgi complex
| - -cell membrane
62
What is the Golgi apparatus?
system of cisternae ("transfer station")
63
What does the Golgi apparatus synthesize?
- carbs
| - finishing touches on proteins
64
Where are vesicles sorted and repackaged?
Golgi apparatus
65
How does the Golgi apparatus modify newly synthesized proteins?
Receives newly synthesized proteins from rough ER
| --modifies via splicing (cutting amino acid sequence) and adding/removing sugars
66
Where do proteins assemble?
on surface of ER
67
How are proteins assembled?
-threaded through a pore in the ER membrane not cisterna
68
What happens in post-transitional modification?
- remove amino acid segments
- fold protein
- stabilized protein
- -disulfide bonds
- add carbohydrates
69
What happens when the rough ER is finished with protein processing?
a transport vesicle would bubble off of surface of rough ER and carry the protein to the Golgi complex
70
What happens when the protein is transported to the Golgi apparatus?
further modification go protein and carbohydrates added
71
After proteins are done modifying at the Golgi apparatus, what happens?
proteins bud off into cytoplasm
| --some then become lysosomes or migrate to the cell membrane
72
Genes can be turned __ and __
| Some cells can even turn some genes ____ ____
- on
- off
- permanently off
73
True or false:
| cells can turn genes on only when needed
True
| this can be controlled by chemical messengers such as hormones
74
What are enzymes?
| easy definition and official definition
- protein catalyst
| - biological catalyst that enable biochemical reactions to occur rapidly at normal body temperature
75
What can enzymes do?
1. increase the rate of a reaction
2. reusable- not changed by reaction
3. doesn't change the nature of the reaction (could occur, super slow)
4. lower the activation energy
5. enzymes work fast
76
Activation energy definition
energy required for a reaction to occur
77
what happens with activation energy?
- orient substrate molecules in a precise way
- rearrange the electrons in the substrate
- strain the bond of substrate (force closer together, force reaction)
78
Why must enzymes come into contact with reactants (substrates)?
1) Substrate binds to enzyme
2) From enzyme - substrate complex
3) Break down --> products/enzyme
79
What happens in the first step of enzymatic reactions?
1. Substrate becomes bound to the enzyme
| - -binds on active site (region where substrate binds to)
80
What happens in the second step of enzymatic reactions?
2. Enzyme-substrate complex
| lock-and-key and Induced fit
81
What are the two models of the enzyme substrate complex?
1. Lock-and-key --> enzyme substrate fit specifically
| 2. Induced fit --> shape change
82
What happens in the third step of enzymatic reactions?
3. Breaks down to release products and enzyme
| - -bond broken by hydrolysis = reaction products
83
How is the concentration of enzymes measured?
Via rate of conversion of substrate to product- rate of enzyme activity
84
What is the rate of enzyme activity?
how quickly a product is produced
85
What can effect the rate of enzyme activity (rate at which substrates are converted to products)
- temperature and pH
- concentration of cofactor/coenzymes
- concentration of enzyme itself
- concentration of substrate
- influence of products on the ability of others to take place
86
What specifically does temperature and pH do to enzyme activity?
- Can alter the ability of enzyme to bind to substrate
- enzymes vary in optimum pH
- Temperature optimum for human enzymes (37 degrees C)
87
Some metal ions function as ____ for enzymes
cofactors
| bind to enzyme --> change the conformation
88
Some organic molecules function as ____ - directly participate as a substrate in a chemical reaction
coenzymes
89
What do transfer stations do?
Move molecules around and detect transporters
90
What does the mitochondria contain and what is it surrounded by?
- Organelles specialized for synthesizing ATP
- Surrounded by a double membrane (inner membrane - folds and spaces and matrix- contains ribosomes, enzymes for ATP synthesis, and mitochondrial DNA
91
What is most important for energy transfer molecule?
Adenosine triphosphate (ATP)
92
Hydrolysis of ATP is catalyzed by ____
Adenosine triphosphatases (ATPases)
93
Phosphorylation Definition and Equation
-Addition of a phosphate group to a molecule
| ATP + H20 ---(ATPase---> ADP + Pi + Energy
94
What does instability do in the use and production of ATP?
instability is the effective energy carrier
95
What does glycolysis do and where does it take place?
- splits glucose into pyruvate
| - happens in the cytosol
96
What is Aerobic Respiration apart of and where does it take place?
- Citric Acid Cycle
| - Electron Transport Chain
