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267 Cards in this Set
- Front
- Back
Eukaryotic cells sequester most of their DNA in the ___.
|
nucleus
|
|
The nucleus occupies about ___% of cell volume.
|
10
|
|
T/F: Nuclei may be spherical, elongated, flattened or lobed depending on the cell type.
|
true
|
|
Nuclei are usually located in the ___ of cells, although there are exceptions.
|
center
|
|
T/F: All cells at some point have a nucleus.
|
true
|
|
An example of a cell without a central nucleus
|
fat cell
|
|
the five main structures of the nucleus
|
nuclear envelope
chromatin nuclear matrix nucleoli nucleoplasm |
|
the fluid substance in which the solutes of the nucleus are dissolved
|
nucleoplasm
|
|
T/F: Nucleoplasm is analogous to cytoplasm.
|
false
|
|
The ___ is a protein-containing fibrillar network, the insoluble material left in the nucleus after a series of biochemical extraction steps.
|
nuclear matrix
|
|
The nuclear matrix is thought to act as a ___.
|
scaffold
|
|
The constituent proteins of the nuclear matrix may bind ___, which could serve several functions.
|
chromosomes
|
|
functions of the constituent proteins of the nuclear matrix binding chromosomes
|
1. help organize chromosomes (localize genes)
2. help regulate gene expression 3. help regulate DNA replication |
|
The ___ separates the eukaryotic cell's genetic material from the cytoplasm.
|
nuclear envelope
|
|
The nuclear envelope serves as a ___ regulating ___ of materials.
|
barrier
entry and exit |
|
The nuclear envelope consists of the ___ and ___ membranes.
|
inner
outer |
|
The inner and outer membranes of the nuclear envelope are about ___ nm apart.
|
10-50
|
|
The inner and outer membranes of the nuclear envelope are fused together at regularly interspersed circular passageways known as ___.
|
nuclear pores
|
|
The space between the two membranes of the nuclear envelope is known as the ___.
|
perinuclear space
|
|
The inner and outer nuclear membranes are ___ but have different ___.
|
continuous
functions |
|
The inner and outer nuclear membranes maintain distinct ___ compositions.
|
protein
|
|
The inner nuclear membrane contains proteins specialized to bind the ___.
|
nuclear lamina
|
|
a thin meshwork of intermediate filament proteins covering the inside surface of the inner membrane
|
nuclear lamina
|
|
Three functions of the nuclear lamina:
1. provides ___ for the inner membrane 2. a site of attachment for ___ 3. has a presumed role in ___ |
1. mechanical support
2. chromatin 3. DNA transcription and translation |
|
The filaments of the nuclear lamina are composed of proteins called ___.
|
lamins
|
|
___ mutations are responsible for various human diseases such as Hutchinson-Guilford progeria syndrome.
|
lamin gene
|
|
a disease caused by lamin gene mutations which causes premature aging and death during teen years
|
Hutchinson-Guilford progeria syndrome
|
|
The outer nuclear membrane is continuous with the membrane of the __.
|
ER
|
|
The ___ is continuous with the ER lumen.
|
perinuclear space
|
|
The outer membrane is studded with ___.
|
ribosomes
|
|
The outermembrane of the nuclear envelope is supported by a loosely organized network of ___.
|
intermediate filaments
|
|
The average mammalian cell nucleus is peppered with several thousand ___.
|
nuclear pores
|
|
Associated with each nuclear pore is a ___.
|
nuclear pore complex (NPC)
|
|
The nuclear pore complex is a hub of activity with a large volume of ___ traffic.
|
bi-directional
|
|
The ___ is a basket-like apparatus consisting of about ___ different proteins (___).
|
nuclear pore complex (NPC)
30-50 nucleoporins |
|
The ___ fills the nuclear pore like a stopper.
|
nuclear pore complex (NPC)
|
|
The basket portion of the NPC "hangs" into the ___.
|
nucleus
|
|
NPCs move material across the ___ in both directions.
|
nuclear membrane
|
|
___ molecules may freely diffuse through the aqueous pores in the NPC.
|
small water-soluble
|
|
Larger molecules move through the NPC via ___.
|
active transport
|
|
NPCs provide a relatively large channel through which molecules can pass without ___.
|
restructuring
|
|
T/F: Proteins may pass fully folded through the NPC.
|
true
|
|
___ subunits may pass fully assembled through NPCs.
|
ribosomal
|
|
For the import of molecules through the nuclear pores into the nucleus, nuclear proteins must bear a ___ (NLS).
|
nuclear localization signal
|
|
The NLS-protein binds ___, and the resulting complex associates with a cytoplasmic filament.
|
importins
|
|
Steps in the import of molecules into the cell nucleus
|
1. Nuclear proteins bearing a nuclear localization signal (NLS) binds importins
2. The resulting complex associates with a cytoplasmic filament 3. The filament guides the complex through the pore 4. NLS-protein is released on the nuclear side 5. Importins are transported back to the cytoplasm (energy of GTP is required) |
|
Proteins exported from the nucleus contain ___ (NES).
|
nuclear export signals
|
|
Most cytoplasm-bound molecules are ___.
|
mRNAs
|
|
A protein complex binds newly synthesized mRNAs to guide them through the ___ into the ___.
|
NPC
cytoplasm |
|
the basic building block of DNA
|
nucleotide
|
|
a dense-staining region of the nucleus; a large aggregate of macromolecules needed for the assembly of ribosomes
|
nucleolus
|
|
The nucleolus is a large aggregate of macromolecules needed for the assembly of ___.
|
ribosomes
|
|
T/F: The nucleolus does not have a membrane.
|
true
|
|
the main components of the nucleolus
|
proteins
rRNAs (ribosomal RNA) rRNA genes (located on certain chromosomes) |
|
T/F: Nucleoli are capable of fusion.
|
true
|
|
The nucleolus disassociates at the beginning of ___ and then reforms at its conclusion.
|
mitosis
|
|
five unifying characteristics of life
|
organization
metabolism reproduction development cellular composition (all living things are made up of cells) |
|
"All living things are made up of cells"
|
cellular composition
|
|
There are over ___ cell types in the human body.
|
200
|
|
All cells arise from ___ cells. This is true of both unicellular and multicellular organisms.
|
preexisting
|
|
In multicellular organisms, the ___ gives rise to all other cells that make up the organism.
|
egg cell
|
|
The egg contains ___ that is being faithfully passed along to all other cells.
|
hereditary information
|
|
Without exception, all living things on earth store hereditary information in long chemical polymers known as ___.
|
deoxyribonucleic acids (DNA)
|
|
All information regarding an organism is stored in just ___ strung together in long linear sequences (DNA).
|
four monomers
|
|
the four monomers in which all information regarding an organism is stored
|
the nucleotides A, C, G, and T
|
|
T/F: The four nucleotides are quite sufficient to store the complexity of an entire genome.
|
true
|
|
The ___ is the basic monomeric building block of DNA (and RNA).
|
nucleotide
|
|
the three basic parts of a nucleotide
|
a sugar (pentose)
a nitrogenous base a phosphate group |
|
the two types of sugars (monosaccharides) found in nucleotides
|
riboses (RNA)
deoxyriboses (DNA) |
|
the two types of bses in DNA
|
purines
pyrimidines |
|
1. ___ consist of two rings.
2. ___ consist of one ring. |
1. purines
2. pyrimidines |
|
the two purines
|
guanine
adenine |
|
the three pyrimidines
|
cytosine
thymine uracil |
|
T/F: Nucleotides are polarized molecules.
|
true
|
|
the two distinct ends of nucleotides
|
5'
3' |
|
The 5' end of a nucleotide is the location of the ___ group; the 3' end is the location of the ___ group.
|
phosphate
sugar |
|
Stacked nucleotides form a single DNA strand and give the molecule ___.
|
polarity
|
|
Adjacent (stacked) nucleotides are bound from ___ to ___.
|
phosphate
sugar |
|
The adjacent (stacked) nucleotides are bound from phosphate to sugar (deoxyribose), creating a sugar-phosphate ___.
|
backbone
|
|
Nucleotide ___ project from the backbone.
|
bases
|
|
In 1953, ___ and ___ proposed a structural model for DNA - the double helix.
|
Watson
Crick |
|
In 1953, Watson and Crick proposed a structural model for DNA - the ___.
|
double helix
|
|
The Watson-Crick Model:
1. The DNA molecule is composed of ___. 2. The strands ___ around each other. 3. The strands are ___ and ___. 4. The sugar-phosphate backbones are on the ___ of the molecule. 5. The bases project ___. 6. The two strands are held together by ___ between opposite bases. |
1. two strands of nucleotides
2. spiral 3. antiparallel, complementary 4. outside 5. inward 6. hydrogen bonds |
|
Nucleotides:
C's and ___ go together; A's and ___ go together. |
G's
T's |
|
A-T have ___ H bonds (2); C-G have ___ H bonds (3).
|
weaker
stronger |
|
___ are the principal building blocks of all organisms.
|
proteins
|
|
T/F: Proteins can only function in a certain configuration.
|
true
|
|
Protein configuration is determined by ___. This sequence is determined by ___.
|
amino acid sequence
nucleotide sequence in DNA |
|
___ contains an organism's genetic information, encoded in the linear organization of nucleotides.
|
DNA
|
|
An organism's genetic information is contained in the linear organization of the ___ of the DNA.
|
nucleotides
|
|
An organism's genetic information must be transmitted to the protein synthesizing machinery - the ___ allows for RNA transcription.
|
double helix
|
|
the segment of DNA (series of base pairs) corresponding to a single protein or RNA
|
gene
|
|
a distinct unit of inheritance which determines the characteristics of species and individuals
|
gene
|
|
a body (structure) in the cell nucleus that contains genes
|
chromosome
|
|
Chromosomes are composed of ___ and associated ___.
|
DNA
proteins |
|
Word root of chromosome:
chromo = ___ some = ___ |
colored
body |
|
The stereotypical representation of a chromosome is really only visible during ___ of the cell cycle.
|
mitosis (metaphase, or mitotic, chromosome)
|
|
T/F: For a significant part of the cell cycle, nuclear DNA does not take the form of chromosomes.
|
true
|
|
For a significant part of the cell cycle, nuclear DNA has a ___ appearance and is composed of ___.
|
puffed, stringy
chromatin |
|
In preparation for cell division, nuclear DNA must be ___.
|
replicated
|
|
Following replication, DNA must organize itself in a manner allowing it to be evenly distributed to two new ___, i.e., chromatin organizes itself into ___.
|
daughter cells
chromosomes |
|
A chromosome as we see it during mitosis is really a ___.
|
pair of chromosomes
|
|
pair of chromosomes = ___
|
homologous chromosomes
|
|
There are normally ___ chromosomes in human somatic cells (___ from each parent).
|
46
23 |
|
Since we have two of each chromosome (homologous chromosomes), we also have two of each ___ on the chromosome.
|
gene
|
|
Since we have two of each chromosome, we also have two of each gene on the chromosome; corresponding genes are likely to be ___.
|
different
|
|
Each copy of a gene is referred to as an ___.
|
allele
|
|
the part of the chromosome where a gene is located
|
locus
|
|
different forms of a gene at a gene locus, often denoted by letters such as A or a
|
alleles
|
|
The presence of two copies of the same gene allows for ___ of one allele over another.
|
dominance
|
|
The presence of two copies of the same gene allows for dominance of one allele (___ gene) over another (___ gene).
|
dominant
recessive |
|
If a trait is recessive (e.g., albinism), an individual must carry two ___ (one from each parent) in order for the trait to manifest itself.
|
recessive alleles
|
|
The ___ is all the DNA - coding and non-coding - occurring in one haploid (23 chromosomes) set of chromosomes in one individual.
|
genome
|
|
The ___ represents the collective body of information present in a species.
|
genome
|
|
In humans, the genome consists of ___ base pairs.
|
about 3.1 billion
|
|
The average DNA molecule (chromosome) is ___ long and ___ thick.
|
2 inches
2nm |
|
Keeping the proportion of DNA's length and thickness, an 8-inch thick telephone pole would rise ___ above the earth.
|
2500 miles
|
|
___ total meters of DNA must be correctly packaged into every nucleated cell.
|
2
|
|
A nucleus ___ in diameter must pack in DNA ___ times this length.
|
10 micrometers
200,000 |
|
T/F: Chromosomes can seemingly appear out of nowhere and suddenly disappear.
|
true
|
|
The organization of DNA within chromosomes exists on a spectrum from ___ to incredibly ___.
|
diffuse
compact |
|
In a ___ cell, chromosomes are fairly diffuse (chromatin).
|
non-mitotic
|
|
In a ___ cell, chromosomes are very compact (sister chromatids)
|
mitotic
|
|
___ represent the lowest level of chromosomal organization.
|
nucleosomes
|
|
A ___ is a unit consisting of DNA wrapped multiple times around a complex of histone proteins.
|
nucleosome
|
|
A nucleosome is a unit consisting of DNA wrapped multiple times around a complex of ___ proteins.
|
histone
|
|
Nucleosomes are joined together like ___ to form chromatin.
|
beads on a string
|
|
Nucleosomes are joined together like beads on a string to form ___.
|
chromatin
|
|
The next level of chromatin organization after being formed from nucleosomes features organized packaging into ___.
|
30nm fibers
|
|
Nucleosomes in a 30 nm fiber are thought to be packaged in two ways: ___ and ___
|
zig-zag
solenoid |
|
Nucleosomes organize to ___; next to ___; then to ___; then to ___; then to ___.
|
chromatin
30nm fibers loops 300nm fiber sister chromatids |
|
A further level of chromatin organization features irregular ___ of 30nm fibers; these are then tethered to proteins forming a scaffold and then they coil to form a ___.
|
loops
fiber about 300nm in diameter |
|
The 300nm looped chromatin fibers perform a final coil to form ___. This final coil shortens the DNA ___fold.
|
sister chromatids (700 nm diameter)
10 |
|
The ___ chromosome represents the ultimate in chromatin organization and compactness.
|
metaphase
|
|
1 micrometer of metaphase chromosome contains ___ of DNA (packing ration of ___).
|
1 cm
10,000:1 |
|
A gene is said to be expressed when its genetic information is transferred to ___ and then to ___.
|
mRNA
protein |
|
DNA to mRNA = ___
|
transcription
|
|
transcription = ___ to ___
|
DNA
mRNA |
|
mRNA to protein = ___
|
translation
|
|
translation = ___ to ___
|
mRNA
protein |
|
The flow of genetic information from DNA to RNA to protein is common to all cells - this flow is termed the ___.
|
central dogma of molecular biology
|
|
the same information transferred from one format to another
|
transcription
|
|
Our genetic information is stored in the cell ___ as ___.
|
nucleus
DNA |
|
the two ways our genetic information stored as DNA in the cell nucleus is used
|
1. it must be passed along to daughter cells (DNA replication)
2. it must be copied in order to make proteins for use in the current cell (RNA synthesis, i.e, transcription) |
|
the two basic constraints the cell must overcome in obtaining protein from DNA; the solution to these problems is ___
|
1. segregation of cellular activities
2. size of DNA molecules transcription |
|
Chromosomal DNA resides in the ___; the synthesis of proteins takes place in the ___.
|
nucleus
cytoplasm (so info from DNA must be transferred to the cytoplasm) |
|
Chromosomal DNA totals ___ base pairs (the entire genome).
|
3.2 billion
|
|
T/F: If the cell needs to synthesize a specific protein, only information from a few thousand base pairs may be required.
|
true
|
|
In transcription, the cell needs a method of extracting the ___ from a long strand of DNA.
|
short segment of information required
|
|
___ is the intermediate between a gene and its protein.
|
mRNA
|
|
___ is a small, mobile nucleic acid which carries information from the nucleus to the cytoplasm.
|
mRNA
|
|
RNA is similar to DNA in that both molecules are composed of ___.
|
nucleotides
|
|
Major differences between DNA and RNA molecules:
1. DNA is composed of the sugar ___; RNA's sugar is ___. 2. DNA contains ___, RNA contains ___ to pair up with adenine. 3. DNA forms a double-___; RNA forms ___. |
1. deoxyribose
ribose 2. thymine uracil 3. helix varied structures |
|
RNA is composed of the sugar ___.
|
ribose
|
|
DNA is composed of the sugar ___.
|
deoxyribose
|
|
DNA serves as a ___ from which mRNA is assembled (transcription).
|
template
|
|
mRNA assembly
|
transcription
|
|
The mRNA transcript migrates from the nucleus to a ___ where translation occurs (protein assembly).
|
ribosome
|
|
protein assembly = ___
|
translation
|
|
Polymerases are ___.
|
enzymes
|
|
Transcription is catalyzed by enzymes known as ___.
|
RNA polymerases
|
|
RNA polymerases produce a single-strand RNA that is ___ to one strand of DNA.
|
complementary
|
|
RNA polymerase binds to a region of DNA called the ___.
|
promoter
|
|
In transcription, attachment of the ___ causes the DNA to unwind and the two strands to separate.
|
RNA polymerase
|
|
In transcription, after attachment of the RNA polymerase causes the DNA to unwind and the two strands to separate, complementary ___ bind to one strand of DNA.
|
RNA nucleotides
|
|
In transcription, after attachment of the RNA polymerase causes the DNA to unwind and the two strands to separate and complementary RNA nucleotides bind to one strand of DNA, the RNA polymerase then assembles the nucleotidews into a(n) ___.
|
mRNA chain
|
|
T/F: RNA polymerases operate somewhat differently in prokaryotic cells vs. eukaryotic cells.
|
true
|
|
T/F: The details of eukaryotic transcription are simpler and were elucidated first.
|
false (prokaryotic is simpler)
|
|
In both prokaryotes and eukaryotes, RNA polymerases much search for a ___ region on the DNA.
|
promoter
|
|
The promoter region of a gene indicates a ___ for transcription of an mRNA.
|
start site
|
|
The promoter region of a gene indicates a start site for ___.
|
transcription of an mRN
|
|
Promoter regions are highly ___. In eukaryotes this is known as the ___ for the heavy presence of thymines and adenines.
|
conserved (present across species)
TATA |
|
Prokaryotic RNA polymerases form loose associations with the DNA and require the help of an accessory polypeptide, called the ___, to find the correct start site for transcription.
|
sigma factor
|
|
T/F: Sigma factor separates from the RNA polymerase following the initiation of transcription.
|
true
|
|
Eukaryotic RNA polymerases cannot initiate transcription without a series of ___.
|
protein factors
|
|
the series of protein factors required for eukaryotic RNA polymerases to initiate transcription (to correctly position the RNA polymerase at the promoter)
|
general transcription factors
|
|
T/F: In both eukaryotes and prokaryotes, RNA polymerase will cause unwinding of the DNA helix and separation of the strands
|
true
|
|
In transcription in both eukaryotes and prokaryotes, ___ nucleotides of the DNA are separated at a time.
|
20
|
|
In transcription in both eukaryotes and prokaryotes, 20 nucleotides of the DNA are separated at a time - called the ___.
|
transcription bubble
|
|
the one strand of DNA that serves as a template from which an RNA molecule will be synthesized
|
template strand
|
|
RNA polymerase must locate a gene's ___ in order to initiate transcription.
|
promoter
|
|
T/F: A gene contains only one promoter
|
true
|
|
The strand containing the promoter serves as the ___ strand.
|
template
|
|
T/F: In theory two mRNA's could be obtained from a DNA molecule.
|
true
|
|
RNA is transcribed from the template strand of ___, and a ___ RNA strand is synthesized.
|
DNA
complementary |
|
When RNA is transcribed from the template strand of DNA, the actual information contained in the RNA is ___ to the other (non-template) strand.
|
identical
|
|
When RNA is transcribed from the template strand of DNA, the actual information contained in the RNA is identical to the ___ strand.
|
other (non-template) strand
|
|
The non-template strand is sometimes referred to as ___ and the template strand as ___.
|
sense
antisense |
|
RNA polymerases move along the DNA strand in a ___ , direction.
|
3' to 5'
|
|
RNA is synthesized in a ___ direction.
|
5' to 3'
|
|
In RNA synthesis, nucleotide triphosphates are added at the ___ end.
|
3'
|
|
Elongation occurs at about ___ nucleotides/sec.
|
50
|
|
T/F: RNA polymerase can move in either direction relative to the double-stranded DNA molecule.
|
true
|
|
T/F: RNA polymerase can only move in one direction relative to the template strand.
|
true
|
|
RNA polymerase can move in either direction relative to the ___ molecule, but it can only move in one direction relative to the ___ (3' to 5' direction).
|
double-stranded DNA molecule
template strand |
|
T/F: In both eukaryotes and prokaryotes, the configuration of DNA can present obstacles to the RNA polymerase (chromatin structure, DNA supercoiling).
|
true
|
|
T/F: Because of obstacles to the RNA polymerase, the movement of RNA polymerase is usually not smooth.
|
true
|
|
2 obstacles to the RNA polymerase found in the configuration of DNA
|
chromatin structure
DNA supercoiling |
|
Both prokaryotic and eukaryotic RNA polymerases require ___ to navigate DNA during transcription.
|
proteins
|
|
___ prevent RNA polymerases from detaching prematurely.
|
elongation factors
|
|
___ and ___ reduce DNA supercoiling.
|
DNA gyrases
topoisomerases |
|
In both prokaryotes and eukaryotes, the signal for termination is encoded in the ___.
|
gene (a specific DNA sequence)
|
|
In prokaryotes, termination is essentially a ___ event that follows elongation.
|
single step
|
|
In eukaryotes, termination occurs in conjunction with an ___ that prepare the mRNA for translation.
|
intricate series of processing steps
|
|
In prokaryotes, RNA polymerase looks for a consensus sequence in the gene, called the ___, that tells it to stop.
|
terminator
|
|
In prokaryotes when the RNA polymerase finds the terminator, the polymerase stops and releases both the ___ and the ___.
|
DNA template
new mRNA |
|
After termination, the RNA polymerase searches for a new ___ so that transcription may start again.
|
sigma factor
|
|
The terminator is thought to code for an ___ structure.
|
RNA hairpin
|
|
The RNA hairpin structure coded for by the terminator "derails" the RNA polymerase releasing ___, ___ and ___.
|
DNA
RNA polymerase |
|
The terminator is an ___ rich sequence.
|
A-T
|
|
The DNA-RNA hybrid of the terminator is formed mainly by ___ base pairs (two hydrogen bonds are easier to break).
|
A-U
|
|
Transcription in prokaryotes is a relatively straightforward process that occurs in three basic stages: ___, ___ and ___.
|
initiation
elongation termination |
|
The net result of transcription is a transcript ___ that is an unprocessed copy of DNA, ready to be translated.
|
mRNA
|
|
In eukaryotes, the processing of mRNA for final use by the cell occurs ___ transcription, elongation and termination.
|
during and after
|
|
Transcription involves making a copy of all nucleotides between the ___ and the ___.
|
promoter
terminator |
|
T/F: In eukaryotes not all of the transcribed mRNA molecule (pre-mRNA) will code for a protein.
|
true
|
|
Important parts of the pre-mRNA are the ___ which function in the regulation of translation.
|
untranslated regions
|
|
the two important structures that must be part of the final mRNA to be exported from the nucleus
|
1. 7-methyl guanosine cap
2. poly-A tail |
|
___ and ___ ensure the mRNA will be properly exported from the nucleus and interact with a ribosome for translation.
|
a 7-methyl guanosine cap
a poly-A tail |
|
A 7-methyl guanosine cap and a poly-A tail ensure that the mRNA will be properly exported from the nucleus and interact with a ___ for translation.
|
ribosome
|
|
The pre-mRNA is organized into two basic regions: ___ and ___.
|
introns
exons |
|
___ do not code for the protein and are removed from the pre-mRNA in translation.
|
introns
|
|
These segments of pre-mRNA code for a protein and are eventually spliced together.
|
exons
|
|
the purpose of introns
|
allow one gene to code for several different proteins
|
|
We have about ___ different genes but about ___ different mRNAs.
|
25,000
100,000 |
|
the three basic levels at which gene expression is regulated
|
transcriptional (DNA)
processing (RNA) translational (protein) |
|
mechanisms determining whether and how often a gene is transcribed = ___-level control
|
transcriptional
|
|
nature of mRNA obtained from transcript = ___-level control
|
processing
|
|
mechanisms determining whether and how often an mRNA is translated = ___-level control
|
translational
|
|
An ___ is a simple copy of the DNA from which it was transcribed.
|
mRNA
|
|
Nucleotides are copied as ___.
|
nucleotides
|
|
T/F: Converting mRNA into protein is more complex than transcribing mRNA.
|
true
|
|
In translation, the language of ___ must be translated into the language of ___.
|
nucleotides
amino acids |
|
Proteins are essentially a string of ___.
|
amino acids
|
|
The order of the amino acids in proteins is determined by the order of ___.
|
nucleotides in the gene (DNA)
|
|
the order of nucleotides in the gene = the ___
|
mRNA
|
|
The code for the protein is contained in the sequences of ___.
|
nucleotides
|
|
T/F: In translation, the order of nucleotides in the gene (the mRNA) must be read and translated.
|
true
|
|
mRNA molecules are read in sets of ___.
|
three
|
|
each set of three nucleotides = a ___
|
codon
|
|
Each codon codes for a particular ___.
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amino acid
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T/F: Most amino acids have more than one codon.
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true
|
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Most amino acids have more than one ___.
|
codon
|
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The protein synthesizing machinery must read the mRNA codons, and a ___ determines where reading starts.
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start codon
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A "start" codon determines where reading the mRNA codons starts, and this sets the ___.
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reading frame
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___ are adaptor molecules responsible for matching amino acids to mRNA codons.
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transfer RNAs (tRNAs)
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T/F: Amino acids do not directly recognize a codon, so a tRNA is needed.
|
true
|
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There are many tRNA genes, about ___ of which are known.
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48
|
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tRNAs form a cloverleaf about ___ in length.
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80 nucleotides
|
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the two important regions in the tRNA
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the anticodon
the amino acid binding site |
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The ___ region of the tRNA binds the mRNA codon.
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anticodon
|
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The ___ region of the tRNA carries the appropriate amino acid.
|
amino acid binding site
|
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tRNAs bind ___ from the intercellular pool, which requires the energy of ___.
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amino acids
ATP |
|
After binding amino acids from the intracellular pool, the tRNAs then take the amino acids to the ___ for incorporation into the growing peptide chain.
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ribosome
|
|
There are ___ known codons, but only ___ anticodons (tRNAs).
|
61
48 |
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Since there are 61 known codons and only 48 anticodons, some anticodons must be able to bind to codons that are not an ___.
|
exact match
|
|
T/F: The first twonucleotides of a codon require a stringent base pairing, while the third nucleotide of a codon permits a mismatch.
|
true
|
|
The ___ nucleotides of a codon require a stringent base pairing.
|
first two
|
|
The ___ nucleotide of a codon permits a mismatch.
|
third
|
|
The third nucleotide of a codon permits a mismatch - this is known as ___.
|
wobble base pairing
|
|
___ base pairing allows a codon to base pair with more than one anticodon.
|
wobble
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___ are the site of translation
|
ribosomes
|
|
nucleotide to amino acid = ___
|
translation
|
|
Ribosomes are ___ for the synthesis of protein.
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catalysts
|
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A typical eukaryotic cell may contain ___ ribosomes.
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one million
|
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Ribosomes consist of two molecules: ___ and ___.
|
proteins (over 50 different types)
rRNA |
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The proteins and rRNA of ribosomes are assembled into ___.
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two subunits
|