Chapter 3: Genetic Control of Protein Synthesis, Cell Function, and Cell Reproduction Flashcards
This refers to the entire process from transcription of the genetic code in the nucleus to the translation of the RNA code and formation of proteins in the cytoplasm
gene expression
How are the 2 DNA strands held together?
by hydrogen bonds between the purine and pyrimidine bases
How many pairs of nucleotides are present in each full turn of the helix in a DNA molecule?
10 pairs
How can the DNA control the formation of proteins in the cell?
by means of a genetic code
This is the transfer of cell nucleus DNA code to cytoplasm RNA code
Transcription
The enzyme that moves along the DNA strand and assembles the RNA molecule
RNA polymerase
This refers to the complementary code triplets formed during RNA synthesis
codons
These portions of the RNA will control the sequence of amino acids in a protein to be synthesized in the cell cytoplasm
codons
What is the difference of ribose from deoxyribose?
ribose contains an extra hydroxyl ion
Thymine is replaced by which nucleic acid in RNA?
uracil
This enzyme functions to activate the RNA nucleotides during RNA synthesis
RNA polymerase
What does RNA polymerase add to each nucleotide during RNA synthesis?
2 phosphate radicals to form triphosphates
This is a sequence of nucleotides in the DNA strand, immediately ahead of the gene to be transcribed, to which the RNA polymerase attaches after recognition
Promoter
**The RNA polymerase has an appropriate complementary structure that recognizes this promoter and becomes attached to it, which is the essential step for initiating the formation of RNA.
How many turns of the DNA helix is unwound by RNA polymerase upon attachment to the promoter?
2 turns
How many turns of the DNA helix is unwound by RNA polymerase upon attachment to the promoter?
2 turns
This is the sequence of DNA nucleotides at the end of the DNA gene which causes the RNA polymerase and the newly formed RNA chain to break away from the DNA strand
chain-terminating sequence
What ribose nucleotide base combines with adenine of the DNA strand?
uracil
This is a large, immature, single strand of RNA that is processed in the nucleus to form mature mRNA.
precursor messenger RNA (pre-mRNA)
These are the segments of the pre-mRNA that is removed by the process of splicing
introns
These are the segments of pre-mRNA which are retained in the final mRNA
exons
This type of RNA directs the splicing of pre-mRNA to mRNA
small nuclear RNA (snRNA)
This type of RNA carries the genetic code to the cytoplasm for controlling the type of protein formed
messenger RNA (mRNA)
This is the type of RNA that transports activated amino acids to the ribosomes to be used in assembling the protein molecule
transfer RNA
This is the type of RNA, along with 75 different proteins, form ribosomes
transfer RNA (tRNA)
These are synthetic miRNAs which are short, double-stranded molecules, comprised of 20 to 25 nucleotides, that interfere with expression of specific genes.
small interfering RNA (aka short interfering RNA, silencing RNA, siRNA)
This is the physical and chemical structure on which protein molecules are actually assembled
ribosomes
This is the type of RNA that can regulate gene transcription and translation
microRNA (miRNA)
Approximately how many nucleotides form the single-stranded microRNA? (range)
21-23 nucleotides
What is the chain-initiating (start) codon?
AUG
What are the chain-terminating (stop) codons?
UAA UAG UGA
Approximately how many nucleotides form a tRNA
80 nucleotides
Which nucleotide in the tRNA serves as the attachment site of the amino acid?
adenylic acid (specifically at its hydroxyl group)
This is the specific code in the tRNA that allows it to recognize a specific codon in the mRNA
anticodon
What percentage of the ribosome is constituted by the rRNA?
60%
**the remainder of the ribosome is protein, including about 75 types of proteins that are both structural proteins and enzymes needed to manufacture proteins.
The ribosome functions in association with which two types of RNA during protein synthesis
tRNA and mRNA
How many pairs of chromosomes in the nucleus are responsible for the formation of ribosomal RNA?
5 pairs of chromosomes
Ribosomal RNA is specially processed in the ________, where it binds with ribosomal proteins to form granular condensation products that are primordial subunits of ribosomes
nucleolus
The miRNAs are encoded from the transcribed DNA of genes, but they are not translated into proteins and are therefore often called:
noncoding RNA
These are longer primary precursor RNA transcripts that are involved in the generation of miRNAs
pri-miRNAs
What processes the pri-miRNAs to pre-miRNAs in the nucleus?
microprocessor complex
These are 70-nucleotide, stem loop structures that are processed in the cytoplasm to become miRNAs
pre-miRNAs
This type of RNA can be tailored for any specific sequence of genes. It is designed to avoid nuclear processing by the microprocessor complex and, after it enters the cytoplasm, it activates the RISC, blocking the translation of mRNA.
small interfering RNA (aka short interfering RNA, silencing RNA, siRNA)
**synthetic type of miRNA
This is the enzyme found in the cytoplasm that processes pre-miRNA by assembling an RNA-induced silencing complex (RISC), and generates miRNAs
dicer enzyme
The ________ regulate gene expression by binding to the complementary region of the RNA and repressing translation or promoting degradation of the messenger RNA (mRNA) before it can be translated by the ribosome.
miRNAs
This complex is assembled by the dicer enzyme and works with the miRNA in repressing translation or promoting mRNA degradation
RNA-induced Silencing Complex (RISC)
These are clusters of 3-10 ribosomes that are being attached to a single mRNA at the same time
polyribosomes
The ribozyme that forms peptide bonds between the successive amino acids, thus adding progressively to the protein chain
peptidyl transferase
How many high-energy phosphate bonds are used for each amino acid added to the protein chain?
4
The process by which the two reactive sites left on the two successive amino acids bond with each other, resulting in a single molecule.
peptide linkage
This is one of the two methods by which the cell regulates its biochemical activities by controlling the degree of action of genes and the formation of gene products themselves.
genetic regulation
This is one of the two methods by which the cell regulates its biochemical activities by controlling the activity levels of enzymes that are already formed
enzyme regulation
This permits the different cell types in the body to each perform their specialized functions and provides all living organisms with the ability to respond to changes in their environment.
genetic regulation (or regulation of gene expression)
True or False:
Regulation of gene expression can occur at any point in the pathways of transcription, RNA processing, and translation.
True
This is the sequence of bases contained in the basal promoter of a eukaryotic DNA
TATA box (TATAAA)
** the binding site of TATA-binding protein (TBP) and several other transcription factors
This refers to the collection of several transcription factors that bind to the TATA box
transcription factor IID complex
This is the transcription factor that binds to both the DNA and RNA polymerase 2 while in the TATA box region, to facilitated transcription.
transcription factor IIB
This is located farther upstream from the transcription start site and contains several binding sites for positive or negative transcription factors that can affect transcription through interactions with proteins bound to the basal promoter
upstream promoter
These are regions of DNA that can bind transcription factors, and they can be located a great distance from the gene they act on or even on a different chromosome. They can also be located upstream or downstream of the gene that they regulate.
Enhancers
These are gene sequences that provide a barrier so that a specific gene is isolated against transcriptional influences from surrounding genes.
insulators
**Insulators can vary greatly in their DNA sequence and the proteins that bind to them. One way an insulator activity can be modulated is by DNA methylation, which is the case for the mammalian insulin-like growth factor 2 (IGF-2) gene.
This is a way of modulating the activity of insulators that is exemplified by the mammalian insulin-like growth factor 2 (IGF-2)
DNA methylation
Between the maternal and paternal DNA sequence for the IGF-2 gene, which one is methylated such that the transcription repressor cannot bind to the insulator allowing the expression of the said gene
Paternal DNA
These are small proteins where the DNA winds around in each chromosome
histones
This substance usually acts on directly on the first enzyme in a sequence, rather than on the subsequent enzymes, causing an allosteric conformational change that inactivates it.
the synthesized PRODUCT
**Enzyme inhibition
One can readily recognize the importance of inactivating the first enzyme because this prevents buildup of intermediary products that are not used.
As an example of enzyme activation, the depletion of ATP in the cell causes the formation of cAMP (breakdown product of ATP) that in turn activates which enzyme that will liberate glucose molecules for the replenishment of ATP?
glycogen phosphorylase
This is considered as the central theme to life
DNA-genetic system
Which phase constitutes 95% of the life cycle of the cell?
Interphase
**the interval between mitosis
What is the first step of cell reproduction?
Replication of all DNA in the chromosome
How many hours prior to mitosis is the DNA duplicated?
5 to 10 hours before mitosis
The duplication of DNA is completed after how many hours?
4-8 hours
in what direction does the DNA polymerase add nucleotides along the DNA template strand?
5’ to 3’ direction
This enzyme causes bonding of successive DNA nucleotides to one another, using high-energy phosphate bonds to energize these attachments
DNA ligase
These enzymes uncoil the DNA helixes by breaking the hydrogen bonding between the base pairs of the DNA
DNA helicases
This is the area that will be the template for replication to begin
Replication fork
** the Y shape separation of the 2 DNA strands
Replication progresses only in what direction
5’ to 3’ direction
Which strand of the uncoiled DNA in oriented in the 3’ to 5’ direction toward the replication fork?
Leading strand
Which strand of the uncoiled DNA is oriented in the 5’ to 3’ direction, away from the replication fork?
Lagging strand
This is a short piece of RNA that binds to the 3’ end of the leading strand once the DNA strands have been separated as a starting point for DNA replication
Primer
**these are generated by DNA primase
This is the process by which the DNA polymerases create the new strand
Elongation
These are pieces of DNA added to the strand between primers in the lagging strand
Okazaki fragments
This enzyme joins the Okazaki fragments to form a single unified strand
DNA ligase
These enzymes remove the RNA primers and proofreads the newly formed DNA, checking and clipping off any mismatched or unpaired residues
exonucleases
This enzyme can transiently/reversibly break the phosphodiester bond in the backbone of the DNA strand to prevent the DNA in front of the replication fork from being overwound.
topoisomerase
The process of replication produces two DNA molecules, each with one strand from the parent DNA and one new strand. For this reason, DNA replication is often described as ___________; half of the chain is part of the original DNA molecule and half is brand new.
semiconservative
The repair progress achieved by the same DNA polymerases and DNA ligases that are used in replication
DNA proofreading
Theses are organizations of small, bobbin-like cores wherein small segments of each DNA helix are coiled
histones
**some of the regulatory proteins decondense the histone packaging of the DNA and allow small segments at a time to form RNA
This is the point of attachment of the two newly formed chromosomes after replication
centromere
These are the cellular structures wherein or around which the first events of mitosis take place
centrioles
This refers to the duplicated but still attached chromosomes
chromatids
This cellular structure is a small cylindrical body about 0.4 micrometer long and about 0.15 micrometer in diameter, consisting mainly of nine parallel tubular structures arranged in the form of a cylinder.
centriole
How many centrioles are present in the cell after interphase?
4 centrioles or 2 pairs
This refers to each pair of centrioles along with its attached pericentriolar material
centrosome
This structure, described as a spiny star, are microtubules that grow radially away from each pair of centrioles as the pair move apart from each other
aster
**Some of the spines of the aster penetrate the nuclear membrane and help separate the two sets of chromatids during mitosis
This refers to the complex of microtubules extending between two new centriole pairs
spindle
This refers to the entire set of microtubules plus the two pairs of centrioles in a mitotic cell
mitotic apparatus
This is the phase of mitosis wherein the chromosomes of the nucleus become condensed into well-defined chromosomes
Prophase
This is the stage of mitosis wherein the growing microtubular spines of the aster fragment the nuclear envelope, and multiple microtubules from the aster attach to the chromatids at the centromeres, pulling one chromatid of each pair toward one cellular pole and its partner toward the opposite pole
Prometaphase
These are minute contractile protein molecules which may be composed of the muscle protein actin, extending between the respective spines and, using a stepping action (as in muscle), actively slide the spines in a reverse direction along each other during metaphase
molecular motors
What is the stage of mitosis wherein the chromatids are pulled tightly by their attached microtubules to the very center of the cell?
Metaphase
What part of the mitotic spindle is formed as the chromatids are pulled tightly by their attached microtubules to the very center of the cell?
equatorial plate
How many chromosomes and chromatids are there by the end of the anaphase stage of mitosis?
92 chromosomes (2 sets of 46 daughter chromosomes) 92 chromatids (46 pairs of sister chromatids were separated)
What forms the contractile ring that cause the pinching off during telophase?
microfilaments (actin and myosin)
What are the 3 factors or ways that control the growth of cells?
- Presence of growth factors
- Space for growth
- Presence of secretions
This is a region of repetitive nucleotide sequences located at each end of a chromatid that serves as a protective cap that prevent the chromosome from deterioration during cell division
Telomere
These are considered to be disposable chromosomal buffers that help maintain stability of the genes but are gradually consumed during repeated cell divisions
Telomeres
Each time a cell divides, an average person loses about how many base pairs from the ends of that cell’s telomeres? (range)
30 to 200
This is the enzyme that adds bases to the ends of the telomeres so that many more generation of cells can be produced
telomerase
What chemical (or drug) makes it possible to prevent formation of mitotic spindle and therefore prevent mitosis, even though replication of the DNA continues; hence, resulting to larger cells?
colchicine
This refers to changes in the physical and functional properties of cells as they proliferate in the embryo to form the different body structures and organs
cell differentiation
The differentiation of cells results not from loss of gene but from selective repression of different gene _________
promoters
Electron micrographs suggest that some segments of DNA helixes that are wound around histone cores become so condensed that they no longer uncoil to form RNA molecules. One explanation for this is as follows. It has been supposed that the cellular genome begins at a certain stage of cell differentiation to produce a __________ that forever after represses a select group of genes. Therefore, the repressed genes never function again.
regulatory protein
What is the maximum and potential number of proteins that a human cell can produce, respectively?
Max = 8,000 to 10,000 Potential = 20,000 to 25,000
This is known as the primary organizer of the embryo because it forms a focus around which the remainder of the embryo develops
primordial chordamesoderm
The primordial chordamesoderm differentiates into a _________ that contains segmentally arranged somites and, as a result of inductions in the surrounding tissues, causes the formation of essentially all the organs of the body
mesodermal axis
What structure of the eye is formed when the developing eye vesicles come into contact with the ectoderm of the head and cause the ectoderm to thicken.
lens
**Another instance of induction occurs when the developing eye vesicles come into contact with the ectoderm of the head and cause the ectoderm to thicken into a lens plate that folds inward to form the lens of the eye. Therefore, a large share of the embryo develops as a result of such inductions, with one part of the body affecting another part, and this part affecting still other parts.
This process involves a specific proteolytic cascade that causes the cell to shrink and condense, disassemble its cytoskeleton, and alter its cell surface so that a neighboring phagocytic cell, such as a macrophage, can attach to the cell membrane and digest the cell
programmed cell death or
apoptosis
This is the process, in contrast to programmed cell death, wherein cells die as a result of an acute injury and usually swell and burst due to loss of cell membrane integrity
necrosis
The leakage of cell contents during necrosis results to:
inflammation and injury to neighboring cells
This is an orderly cell death that results in disassembly and phagocytosis of the cell before any leakage of its contents occur, and neighboring cells usually remain healthy
apoptosis
These are the family of proteases that are activated to initiate apoptosis
caspases
**caspases are synthesized and stored in the cell as inactive procaspases
Inactive form of caspases
procaspases
These are normal genes that code for various proteins that control cell adhesion, growth, and division
proto-oncogenes
These are abnormally functioning genes resulting from mutated or excessively activated proto-oncogenes
oncogenes
These are genes which suppress the activation of specific oncogenes
antioncogenes or tumor suppressor genes
This a factor that greatly increases the probability of mutations by the formation of ions that are highly reactive and can rupture DNA strands in tissue cells, causing many mutations
ionizing radiations
These are chemical substances that greatly increase the probability of mutations in cells
carcinogens
Dyes derived from ____ are known to be carcinogenic
aniline
This a factor that greatly increases the probability of mutations as it leads to rapid mitotic replacement of the cells, the more rapid the mitosis, the greater the chance for mutation
physical irritants
These oncoviruses are capable of inserting itself directly into one of the chromosomes, thereby causing a mutation that leads to cancer
DNA viruses
This is the enzyme of some RNA viruses that causes DNA to be transcribed from RNA which will then be inserted into the animal cell genome, leading to cancer
reverse transcriptase
These are produced by cancer cells that cause many new blood vessels to grow into the cancer, thus supplying the nutrients required for cancer growth
angiogenic factors
