Cell Phys Exam 2 Flashcards
(128 cards)
1
Q
Where is the nucleus found?
A
in eukaryotic cells
2
Q
All mammalian cells have a nucleus EXCEPT _____?
A
mature red blood cells
3
Q
This surrounds the nucleus and consists of a double membrane
A
nuclear envelope
4
Q
Which part of the nuclear envelope is a lipid bi-layer supported internally by a nuclear lamina?
A
Inner nuclear membrane
5
Q
Which part of the nuclear envelope is a thin dense network of protein filaments?
A
nuclear lamina
6
Q
What is the area between the 2 nuclear membranes that is connected to the inside of the endoplasmic reticulum called?
A
perinuclear space
7
Q
what is a lipid bi-layer connected to the endoplasmic reticulum called?
A
outer nuclear membrane
8
Q
What spans the entire nuclear envelope?
A
The nuclear pore complex
9
Q
What does the nuclear pore complex consist of?
A
- 2 parallel rings with 8 subunits outlining the ring
- a central granule called the transporter
10
Q
What is the function of the nuclear pore complex?
A
to transport macromolecules across the nuclear envelope
11
Q
What materials does the nuclear pore complex transport?
A
RNA, ribosomal sub-porteins, carbs, signaling molecules, lipids, etc.
12
Q
What is an acidic nuclear protein involved in transporting through nuclear pores and within nuceloplasm called?
A
Nucleoplasmin
13
Q
What do exportins and inportins do?
A
they are proteins that transport materials
14
Q
what is the fluid portion containing enzymes and RNA called?
A
nucleoplasm
15
Q
What is found in the nucleoplasm?
A
chromosomes
16
Q
What do chromosomes contain?
A
DNA to special proteins
17
Q
What is the complex of DNA and protein in the chromosomes called?
A
Chromatin
18
Q
What proteins is a primary protein of chromatin that cause chromatin packing and helps in gene regulation?
A
Histone Proteins
19
Q
Bead-like structures created by “spools of DNA” are called?
A
nucleosomes
20
Q
Nucleosomes consist of _______ & _______
A
- Wrapped DNA
& - Protein core of 8 histone molecules.
21
Q
What is chromatin remodeling complex?
A
- proteins that us ATP to change nucleosome structure and is necessary for transcription, replication and repair.
22
Q
Which chromatin is less dense and more active DNA, only type of chromatin in prokaryotes and the more active the cell is the more it should have of this?
A
Euchromatin
23
Q
Which chromatin is tightly packed or condensed, not likely to be undergoing transcription, often peripheral in nucleus, and functions for gene regulation and chromosome protection?
A
Heterochromatin
24
Q
This is composed of DNA, RNA and proteins, lacks a membrane and usually has 1-4/nucleus
A
Nucleoli
25
What are the 3 function of the nucleolus
1. make rRNA
2. make proteins necessary for ribosomes
3. make daughter nucleoli
26
What are the functions of the nucleus?
1. reproduction of the cell
2. heredity
3. control all cell functions
27
DNA ----> RNA is called?
Transcription
28
RNA -----> Proteins is called?
Translation
29
What are the two types of proteins?
1. Structural
| 2. Dynamic
30
What are nucleic acids?
- genetic material of cells and viruses
| - present in the nucleus and cytoplasm
31
What are the 2 important types of nucleic acids?
1. DNA
| 2. RNA
32
Which nucleic acid is most in the nucleus, and carries genetic info for protein synthesis?
DNA
33
What is a gene?
a segment of DNA that determines a specific sequence of amino acids in a particular protein
34
What is a genome?
1 complete DNA copy
35
What is a mitochondrial genome?
single circular DNA obtained from the mother
36
what is a nuclear genome?
DNA within 1 chromosome set; for example in an ovum or sperm there is a haploid set of chromosomes created by meiosis.
37
Which chromosomes have on complete DNA strand, proteins, centromere, and telomeres?
Eukaryotic chromosomes
38
what is an area where 2 parts touch called in a DNA structure?
centromere
39
what is a repeating sequence at each end of DNA structure called?
telomeres
40
What are chemical subunits made of?
nucleotides
41
What are the 3 parts to a DNA nucleotide?
1. one phosphate group
2. one pentose sugar
3. one nitrogenous base
42
What are the two categories to DNA nitrogenous bases?
Purines
| Pyrimidines
43
What is a purine and what are the two subunits?
- a double ringed structure
1. Adenine (A)
2. Guanine (G)
44
What is a pyrimidine and what are the two subunits?
- a single ringed structure
1. Cytosine (C)
2. Thymine (T)
45
What are the 5 main points to remember about the Watson and Crick's DNA model?
1. two DNA strands are twisted in a double helix
2. Each strand is a linear arrangement of subunits called nucleotides
3. DNA bases pair in a specific way:
A-T and G-C
4. The 2 strands join at the nitrogenous bases using weak hydrogen cones. Why weak H bonds? because it needs to be unzipped to make proteins and copied.
5. Nucleotides are joined by linking the phosphate on the 5' end to the deoxyribose of on on the 3' position.
46
How many bonds are between A and T?
2 H bonds
47
How many bonds are between G and C?
3 H bonds
48
An example of nucleotide linkage:
If 1 DNA strand is untwisted and has an orientation of 5' to 3' then its complement strand will run 3' to 5'. The nitrogenous base will pair to the 1' carbon and the phosphate bonds at the 5' carbon position
49
RNA is found where?
mostly in the cytoplasm
50
RNA structure is made of subunits called?
ribonucleic acids
51
What are the 3 parts to a ribonucleic acid?
1. A phosphate group
2. A pentose sugar (Ribose)
3. A nitrogenous base
52
RNA is usually single stranded but it is folded with loops it is...
tRNA
53
There are 2 purines and 2 Pyrimidines in RNA name the subunits respectively:
Purines- Adenine, Guanine
Pyrimidines- Cyostine and Uracil
(Note: RNA has U instead of T)
54
What is the function of Messenger RNA (mRNA)
- carries genetic info from nucleus to cytoplasm for protein synthesis.
55
What is a transfer of into from DNA to mRNA called?
transcription
56
What is the function of Transfer RNA (tRNA)?
to decode (translate) the mRNA base sequence into specific amino acid sequence of a particular protein
57
The process of decoding the genetic mRNA message into a protein is called?
Translation
58
What is the function of rRNA?
1. Component of ribosomal structure
2. Binds mRNA to ribosomes
3. Forms peptide bond with adjacent amino acid
59
Since rRNA catalyzes the joining of amino acids rRNA can be called a ?
Ribozyme
60
Rules for copying DNA include:
1. DNA always replicated 3' end to 5' end
2. Base pairing rules apply:
A-T & G-C
3. New DNA is always antiparallel. (Will grow from 5' end to its 3' end.)
61
Ribosomes are found in all cells except:
RBC's, platelets, and mammalian sperm
62
Which cell has more ribosomes eukaryotic cells or prokaryotic cells?
Eukaryotic Cells
63
What are the 3 types of ribosomes?
1. Free Ribosomes
2. Membrane-bound ribosomes (attached to membranes of RER)
3. Parts of a polysome
64
What is a cluster of ribosomes bound to a mRNA called?
Polysome (ergosome)
65
What does S-values indicate?
They indicate size and tells how fast a particle sediments in an ultracentrifuge so cannot add up to the #'s
ex. eukaryotic cytoplasm: 80S
prokaryotic: 70S
mitochondria: 55S
66
What are the 2 parts of a ribosome?
1. Small subunit - on top
| 2. Large subunit - on bottom
67
T/F in ribosomal proteins a large subunit has more than a small subunit?
True
68
What are the two functions of a ribosomal protein?
1. Combine w/rRNA to make ribosomes
| 2. play role in protein synthesis
69
The formation of ribosomes is function of the _____?
Nucleolus
70
What are the 3 steps to form ribosomes?
1. Transcribe genes from rRNA from DNA
2. Process molecules for pre-ribosomal RNA
3. Assemble the ribosome subunits
71
How do ribosomes guid protein synthesis?
1. Properly orientate mRNA, tRNA and amino acids
| 2. rRNA in large subunit acts as a ribozyme, joining amino acids by peptide bonds
72
Where is the mRNA binding site?
in a small subunit
73
Where is the "A" Site (acceptor site) binding site at and its function?
- binds on a large subunit
| - functionally brings in new amino acids during translation
74
Where is the "E" Site (lounge site) exit binding site?
- located behind the P site
| tRNA binds here after it releases amino acids
75
What is the rule for tRNA binding to sites A,P & E?
1. A.A. w/tRNA binds:
1st to A site, 2nd to P site & last to E site.
2. No more than 2 sites contain tRNA at same time
Ex: P & A sites have tRNA or P & E sites have tRNA
76
DNA to DNA is called?
Replication
77
DNA to RNA is called?
Transcription
78
RNA to Protein is called?
Translation
79
How many DNA bases?
4
80
What are the DNA bases?
A,T,G,C
81
How many RNA bases?
4
82
What are the RNA bases?
A,U,G,C
83
What is a codon?
3 bases of DNA or RNA that code for a specific amino acid
| Example: TAC is codon for amino acid methionine
84
How many codons are possible?
4x4x4= 64
85
Do all codons code for amino acids?
61 do: all but 3 which are stop codons ( chain terminators)
86
What type of DNA strand will be copied to make mRNA?
Template Strand
87
What type of strand is a non-template strand and is identical in amino acid sequence as the new mRNA except uracil instead of thymine.
Coding Strand
88
Start codons in DNA=___
TAC (methionine)
89
Start codons in RNA= ___ &___
AUG (methionine) & sometimes GUG (valine)
90
More common amino acids have 4-6 different codons.
| Examples are:
Leucine
| & Serine
91
Least common amino acids have 1 codon. Example:
methionine
92
Code table is NOT random. Most synonyms only differ in the ___ base.
3rd
93
Is the genetic code universal?
NO
94
What are the building blocks needed to make RNA?
-ribonucleotide triphosphates which include ribose, base and phosphate groups.
95
what is an enzyme needed to join nucleotide triphosphates to make RNA called?
RNA polymerase II (in nucleoplasm)
96
This is the process by which information from DNA is converted into its RNA equivalent. The form of RNA from this process is called?
Transcription
| -mRNA
97
The working copies of genes are made of mRNA and occurs in the ______?
Nucleus
98
What are the first 5 steps of transcription sequence?
1. Before transcription, chromatin is packed within histones so DNA is inaccessible.
2. RNA polymerase II enzyme initiates DNA transcription by searching for a promoter site
3. Transcription factors (proteins) bind first to DNA and then RNA polymerase II can bind to the promoter site.
4. The binding of RNA polymerase II to the promoter initiates DNA separation.
5. RNA polymerase II moves along the DNA template strand )= sense strand) & forms temporary H bonds between DNA nucleotide and free ribonucleotides.
99
Alkaline proteins that act as spools in which DNA winds around is?
Histones
100
The promoter site is also a _____ ___ ______
Site of initiation
101
DNA template strands run x'-v' and RNA strands run v'-x'. x and v are?
3-5 and 5-3
102
What is the 6th step in the transcription sequence?
RNA polymerase will then:
A. covalently link adjacent ribonucleotides
B. Release (hydrolysis) 2 phosophates form each ribonucleotide triphosphate
103
What is the 7th step in the transcription sequence?
RNA chain grows until RNA polymerase II transcribes a terminal signal (at 3' end). Then RNA polymerase releases DNA and new RNA strand.
104
What is the 8th step in the transcription sequence?
The new RNA strand= mRNA
- This mRNA is a mirror image of the DNA template "sense" strand. The promoter site indicates which DNA strand will be the template "sense" strand. DNA always reads 3'-5'.
105
What is the 9th-11th steps in the transcription sequence?
9. Error frequency is RNA synthesis = 1 wrong base for every 100000 transcribed.
10. When RNA polymerase reaches a "stop" sequence, it will release the new RNA.
11. AfterRNA released: series of 100-200 adenine nucleotides added to its end= poly A tail.
106
What is a poly A tail?
- not part of DNA
- on 3' ed of the transcribed RNA
- acts as a signal to allow RNA to move out of nucleus and bind to ribosomes in cytoplasm
- Specific function may increase life and time of the mRNA (from mins to hours or days)
107
What % of DNA genes are transcribed into RNA?
10-20%
108
Genes transcribed ONLY when RNA polymerase can bind to the promoter sites : T/F?
True
109
this typo of codon has:
- expression regions
- RNA transcript regions that DO code for sequences of amino acids
- Vary in size: 200 base pairs
- small # of ____ responsible for all proteins
Exons
110
This type of codon has:
- noncoding sequences of nuclotides found between exons
- Estimated 75-95% of human DNA codes for _____
- function is unclear
Introns
111
What is splicing?
The removal of introns
112
What is the purpose of splicing?
1. Leave a continuous sequence of exons.
| 2. To reconnect exons in different sequences because they can create different mRNA sequences from the same gene.
113
Where does splicing occur?
In the nucleus
114
What is a spliceosome?
A protein complex and small nuclear RNA's= snurps= small nuclear ribonucleic-proteins
115
RNA needs to move to the ____ where translation occurs.
cytoplasm
116
What process must occur before transcripted RNA moves into the cytoplasm?
splicing
117
How many base pairs in a DNA promoter site?
several dozen
118
What is important with a DNA promoter site?
1. Determines location of RNA synthesis
2. Determines which DNA strand acts as the template
3. Is the binding site for RNA polymerase II
119
Where is the DNA promoter site located?
Located on the 3' DNA "sense" strand to the left of the start codon TAC
120
What are upstream bases?
- before the TAC codon ( the the left of TAC) these are non coding bases.
121
What are downstream bases?
- to the right of TAC codon these are protein coding bases so start point is always a T.
122
What is an important upstream component?
Core Promoter
123
What part of the core promoter has a short are by the startpoint?
Initiator sequence
124
What part of the core promotor is located at 25 cases upstream?
TATA box (important because RNA polymerase starts with attaching transcription factors to the TATA box)
125
What is an enhanceosome?
a multiprotein complex that activates transcription
126
What are proximal control elements?
a short sequence upstream of the core promoter
127
Where are the proximal control elements located?
to the left of the TATA box and within the 200 nucleotides of the start point
128
What are the 2 parts of the proximal control elements?
1. CAAT box
| 2. GC box
