MCB1 Flashcards
Name 3 cellular organelles present only in eukaryotic cells.
Nucleus, mitochondrion, centriole, lysosome, endoplasmic reticulum.
What is the method of introducing foreign DNA into a bacterium?
Transformation.
What is the name of the gene transfer into prokaryotic and eukaryotic cells?
Into prokaryotic cells: transformation, into eukaryotic cells: transfection.
What is the mechanism of action of penicillin?
Inhibits the formation of bacterial cell wall.
Name the chromosome-containing part of a bacterium.
Nucleoid region.
Name three characteristics of bacterial DNA that distinguish it from eukaryotic DNA.
Shorter, circular, naked, mostly consists of coding region.
What does it mean that viruses are obligate intracellular parasites?
They multiply inside the infected cells only.
What infections can be caused by bacteriophages (2)?
Lytic and lysogenic infection
What is the name of the hypothesis describing the origin of eukaryotic cells?
Endosymbiotic hypothesis.
What parameters influence the resolution power of a light microscope?
Wavelength of light, refractive index, aperture angle of objective lens.
How can you define the limit of resolution?
The shortest distance whose two endpoints can be distinguished from one another.
Name the magnifying components of the light microscope.
Objective lens, ocular lens.
How can you calculate the magnification of the light microscope?
Magnification of objective lens × magnification of ocular lens (eyepiece).
Describe the image that can be seen in the light microscope.
magnified in two steps, inverse, virtual
Name two fixatives used in microscopy.
formaldehyde, glutaraldehyde, osmiumtetroxide, etc.
Which technique is suitable to visualize a specific protein in the cell?
immunocytochemistry
Name two electron microscopic methods which give three dimensional image of the specimen.
angular shadowing, freeze-etching technique, freeze-fracture technique, scanning electron microscopy
Name two electron microscopic methods which are suitable to study isolated organelles.
angular shadowing, rotary shadowing, negative staining, etc.
Which techniques use the deposition of metals on surfaces in electron microscopy? Give two examples.
angular shadowing, rotary shadowing, scanning electron microscopy, replica-technique
Which are the subcellular fractions and in which order are they generated by differential centrifugation?
nuclear fraction mitochondrial fraction → microsomal fraction → ribosomal fraction > cytosol
Which cellular organelles can be found in the microsomal fraction?
Golgi complex, RER (rough endoplasmic reticulum), SER (smooth endoplasmic reticulum)
Which separation methods are used during 2D electrophoresis of proteins?
isoelectric focusing and SDS polyacrylamide gel electrophoresis
What charge do proteins have at the end of isoelectric focusing?
no net charge
What charge do proteins have at the end of SDS polyacrylamide gel electrophoresis?
negative
Which electrophoretic method is suitable for the separation of proteins according to their molecular mass?
SDS polyacrylamide gel electrophoresis
Towards which electrode do nucleic acids move during electrophoresis?
towards the positive electrode
Name 2 separation methods which fractionate particles mostly according to their molecular mass.
gel filtration, SDS polyacrylamide gel electrophoresis, hypopycnic density gradient centrifugation
Name 2 separation methods where fractionation is independent of the molecular mass of the particles.
ion-exchange chromatography, isoelectric focusing, affinity chromatography, isopycnic density gradient centrifugation
During gel filtration, the elution volume of substance ‘A’ is larger than that of substance ‘B’. What conclusion can be drawn from this?
the molecular mass of substance ‘B’ is larger than the molecular mass of substance ‘A’
What kind of ligands can be used during affinity chromatography to separate what kind of substances? Give 2 examples.
antigene-antibody, enzyme-substrate, hormone-receptor, oligo(dT)-poly(A)+ mRNA, etc.
Which separation method is suitable for the separation of poly(A)+ mRNAs from total cellular RNA?
oligo(dT) cellulose affinity chromatography
What type of bonds stabilize the DNA double helix?
H-bonds
What are the basic rules of H-bond formation between bases in nucleic acids?
purines with pyrimidines; A with T (in DNA) or with U (in RNA); G with C (in DNA as well as in RNA)
What are the two main principles of the interaction between the two strands of nucleic acids?
complementarity, antiparallelity
What is the definition of denaturation of nucleic acids?
The disruption of H-bonds
What is a nucleoside composed of?
base + pentose
What is a nucleotide composed of?
base + pentose + phosphate group
Which pentose is found in DNA?
deoxyribose
Which pentose is found in RNA?
ribose
What is the difference between ribose and deoxyribose?
deoxyribose lacks the OH-group at the 2’ C-atom
What bond links the neighbouring nucleotides together in a nucleic acid strand?
phosphodiester bond
What is antiparallelity?
the direction of phosphodiester bonds is opposite in the complementary strands of double-stranded nucleic acids
What is the melting point of DNA?
the temperature required to denature 50% of the DNA sample
What is hyperchromicity?
the increase of UV light absorption during denaturation of DNA
What are purine and pyrimidine bases?
purines: A, G; pyrimidines: C, T, U
In which nucleic acids are the different bases found?
DNA: A, G, C, T; RNA: A, G, C, U
Name a chemical that can precipitate DNA!
ethanol, trichloroacetic acid, etc.
What is the charge of nucleic acids at neutral pH?
negative
What is the reason for the negative charge of nucleic acids?
due to the phosphate groups
Name two chemicals that can cause DNA denaturation!
alkaline solutions, formamide, urea, etc.
Name a chemical that can cause the denaturation of RNA!
formaldehyde
What explains the differences between the melting points of DNA of different species?
the difference between the A+T/G+C ratios in the different DNA molecules
What is a ribozyme?
RNA possessing catalytic activity
Name an acidic amino acid!
aspartic acid, glutamic acid
Name a basic amino acid!
lysine, arginine, histidine
What is the general structure of an amino acid like?
a central C atom attached to four groups: a H atom, a carboxyl group, an amino group and a side chain
What is the primary structure of proteins?
the order of amino acids
Name the bond that links the amino acids together in the primary structure of proteins!
peptide bond
What are the two major forms of the secondary structure of proteins?
a helix, B sheet
What is the name of a functional unit in the tertiary structure of proteins?
domain
What kind of proteins are involved in the folding of proteins in vivo?
chaperones
What makes an amino acid acidic?
carboxyl group in the side chain
Name two proteins possessing quaternary structure!
haemoglobin, insulin
How do enzymes change the activation energy of the catalyzed reactions?
decrease it
Give a definition of the term ‘proteome’!
all the proteins present in a cell
Name two carotenoids!
B-carotene, retinal
Name three steroid compounds!
cholesterol, testosterone, vitamin D
Which steroid is a membrane-component?
cholesterol
Name three hexose sugars!
glucose, galactose, fructose
Name two glucose-polysaccharides!
glycogen, starch
Name two glycosaminoglycans!
chondroitin sulphate, hyaluronic acid
What is the name of the recognition sequence of restriction endonucleases?
palindromic sequence
Give an example for a palindromic sequence containing six base pairs.
GAATTC
Name two types of enzymes that are capable of recognizing palindromic sequences!
restriction endonucleases, modification methylases
What kind of DNA ends can be generated by restriction endonucleases?
blunt ends, cohesive (sticky) ends
Name two methods in which restriction endonucleases have a paramount role!
cloning, genomic library
Name two vectors used in molecular biology!
plasmid, adenovirus
What is the name of the vector the DNA-insert of which can be transcribed in a host cell?
expression vector
Name three sequences that can be isolated only from the genomic library and not from the cDNA library!
promoter, satellite DNA, intron
Would you name the three steps of a PCR cycle in the correct order?
denaturation, primer binding, DNA synthesis
Name two methods used for amplification of a DNA fragment!
PCR, cloning
Name the type of polymerase chain reaction that can be used to quantitate a specific nucleic acid sequence during the reaction!
real-time PCR
What is molecular hybridisation?
Renaturation of a denatured nucleic acid with a labelled probe
Molecular hybridisation is commonly used in various techniques such as in situ hybridisation and northern blotting.
Name two enzymes required to prepare a cDNA library!
Reverse transcriptase, DNA ligase, restriction endonuclease
These enzymes are essential for synthesizing complementary DNA (cDNA) from mRNA.
Which one is tissue specific: a cDNA library or a genomic library?
cDNA library
A cDNA library is derived from mRNA transcripts, reflecting gene expression in specific tissues.
Give an example for the physical, the chemical, and the biological gene transfer!
Physical: microinjection, electroporation, gene gun; Chemical: transfection, liposome; Biological: virus vector
These methods are used to introduce genetic material into cells.
What is the name of animals whose genome contains an artificially introduced gene, and this gene is inherited to the offspring?
Transgenic animals
Transgenic animals are created for various purposes, including research and agriculture.
What does the abbreviation GMO stand for?
Genetically modified organism
GMOs are organisms whose genetic material has been altered using genetic engineering techniques.
Which methods can be used to generate genetically modified organisms (2)?
Microinjection of transgenes into a zygote, manipulation of embryonic stem cells
These methods allow for the introduction of new genetic material into organisms.
What domains do zinc finger nucleases contain (2)?
DNA-binding domain and endonuclease domain
Zinc finger nucleases are designed for targeted genome editing.
What are the two most important molecular components of the CRISPR/Cas9 system?
CRISPR RNA molecule (targeting RNA or guide RNA) and the Cas9 protein
These components work together to enable precise editing of the genome.
What is the function of the targeting RNA (gRNA) in the CRISPR/Cas9 system?
gRNA binds to the specific DNA sequence in the genome by complementary base pairing
This specificity is crucial for the accuracy of genome editing.
What is the role of the Cas9 protein in the CRISPR/Cas9 system?
Cas9 protein is an endonuclease that cleaves both DNA strands of the targeted region
This cleavage is necessary for introducing genetic modifications.
What genetic changes can be induced in a specific region of the genome by targeted gene manipulation techniques (2)?
Gene inactivation (knock out mutation) or gene correction (knock in mutation)
These techniques are used to study gene function and treat genetic diseases.
What is an antisense oligonucleotide?
An oligonucleotide that can inhibit mRNA function by complementary base-pairing
Antisense oligonucleotides are used in therapeutic applications to modulate gene expression.
What is the name of the RNA molecules responsible for RNA interference?
siRNAs
Small interfering RNAs (siRNAs) play a key role in regulating gene expression through RNA interference.
What is the physiological function of siRNAs?
Regulation of gene expression
siRNAs help to silence specific genes, playing a crucial role in cellular processes.
Name a method suitable for specific inhibition of protein function!
Intracellular antibodies, expression of dominant inhibitory proteins, peptidomimetics, competitive inhibitors
These methods can be used to study protein function or develop therapeutic strategies.
Name two methods for the identification of proteins by using specific antibodies!
Immunocytochemistry, immunoprecipitation, Western blotting
These techniques are essential for studying protein expression and interactions.
What is the role of mRNA and oligo(dT) added to an in vitro cDNA synthesizing system?
mRNA: template, oligo(dT): primer
This combination is crucial for synthesizing cDNA from mRNA.
Name two methods capable of proving that the actin gene is expressed in liver cells!
Western blotting, immunocytochemistry, reverse transcription PCR
These methods can confirm gene expression at the protein or mRNA level.
What is the difference between dTTP and ddTTP?
The absence of an -OH group at the 3’-position in ddTTP
This structural difference is critical in DNA synthesis and sequencing.
Write an example of a technique where the nucleic acid probe sequence used is not labeled
sequencing chip, SNP-chip, cDNA-chip
Name the main steps of Illumina sequencing in order
library construction, amplification, sequencing, data analysis
What are the specific properties of the single nucleotide building blocks used in the sequencing step of the Illumina method?
a cleavable blocking molecule is attached to the 3’ OH group of the nucleotide and a fluorescent dye molecule, also cleavable, is attached to its base
What kind of a signal is detected by the machine after incorporation of a nucleotide during Illumina sequencing?
fluorescence
Which scientific term describes the property of simultaneously sequencing a very large number of DNA fragments in case of Illumina and Proton sequencing?
massively parallel
What kind of nucleotides are used in Proton sequencing?
unlabeled, unmodified/normal dNTPs
What change is detected after incorporation of a nucleotide during Proton sequencing?
pH decrease
What kind of nucleic acids can be sequenced using the Nanopore method?
single-stranded DNA or RNA
What kind of signal is detected by the machine during Nanopore sequencing during the incorporation of a nucleotide?
change in current
What are cDNA-chips used for?
to analyze the expression of many (all) genes in a cell
How could you make visible the result of molecular hybridization?
e.g. by autoradiography, fluorescence microscopy
What is the purpose of fluorescence in situ hybridization (FISH)?
localization of a specific nucleic acid sequence by hybridization of a fluorescently labeled probe
What are the types of fluorescence in situ hybridization (FISH) based on the position of the cell along its cell cycle?
interphase FISH and metaphase FISH
What kind of information about the DNA sequence of interest can be obtained from the results of fluorescence in situ hybridization (FISH)?
presence, localization, amount
How many fluorescent signals can be seen in the results of fluorescence in situ hybridization (FISH) in a single healthy diploid cell, when using a probe specific for a given autosomal chromosomal region?
two
Give three examples of the application of fluorescence in situ hybridization (FISH)
analysis of localization of specific genes, analysis of specific chromosomal regions (e.g. telomere, centromere), detection of genetic abnormalities (e.g. deletion, gene amplification, chromosomal translocation), detection of all chromosomes in a cell
Name the main components of the nucleus
nuclear envelope, nucleoplasma, chromatin, nucleolus, nuclear matrix
Which proteins connect chromatin to the inner surface of the nuclear membrane?
lamin proteins
How could you classify heterochromatin on the basis of its location?
marginal/peripheral, nucleolus-associated, diffuse heterochromatin
What is the functional difference between eu- and heterochromatin?
heterochromatin is inactive, euchromatin contains transcriptionally active parts
Name the components of the nucleolus (4)
fibrillar center, fibrillar component, granular component, nucleolus-associated heterochromatin
What is the transport protein and G-protein involved in transport through the nuclear pores?
transport protein: importin, exportin; G-protein: Ran
What is the enzyme activity of Ran?
GTPase
Name the two types of karyopherins
importins, exportins
In what form can DNA be found in interphase cells and in dividing cells?
interphase cells: chromatin, dividing cells: chromosome
Name the chemical components of chromatin (4)
DNA, proteins (histones and non-histones), ions, RNA
Name 2 chemical modifications that are characteristic of histones
phosphorylation, acetylation
What is the difference between constitutive and facultative heterochromatin?
constitutive: permanently inactive form, facultative: in certain circumstances may be activated
What is a nucleosome made of?
histone octamer and DNA
Name the morphological levels of chromatin organisation in the correct order
beads-on-a-string, solenoid, looped domains, metaphase chromosome
Name 2 nonhistone proteins with regulatory function
TATA factor, AP-1, SRE, CREB
Name 2 nonhistone proteins with enzymatic function
RNA polymerases, DNA polymerases, nucleases, ligases
What kind of RNA molecules can be found in chromatin? Name 2 of them
pre-mRNA, pre-rRNA, snRNA, snoRNA
Name a region of chromatids where microtubules bind during cell division
kinetochore, telomeric region
Name the region of chromosomes where sister chromatids are attached to each other
centromere
Give 2 examples of tandemly repeated genes
rRNA genes, tRNA genes, histone genes
Which are the repetitive sequences that can be used as highly polymorphic genetic markers? (2)
minisatellites, microsatellites
Where are the highly repetitive sequences located in the chromosomes? (2)
in the centromeric and telomeric regions
Name a polyglutamine disease
Huntington’s disease
What type of mutation is characteristic of Huntington’s disease?
trinucleotide repeat expansion
What does the abbreviation VNTR stand for?
variable number of tandem repeats
Give 2 examples of proteins coded by gene families
globin, cytoskeleton, cell membrane receptors, protein kinases, transcription factors
What does pseudogene mean?
members of gene families, which became inactive by mutations
What does it mean, that a gene is amplified in the genome?
the increase in the copy number of a gene in the genome
Give an example of a gene amplified in the genome!
rRNA genes, c-myc in certain tumors, etc.
Which human chromosome contains Alu sequences?
all of them
Give an example for a retrotransposon!
viral retrotransposons, Alu sequences, etc.
What are the two main phases of the cell cycle?
interphase and cell division
What are the 3 main phases of the interphase?
G1, S, G2 phases
What is the amount of DNA in a G1 phase cell?
2n, diploid
What is the amount of DNA in a G2 phase cell?
4n, tetraploid
Name a cell type which resides in the G0 phase!
neuron
Name two processes occurring during the S phase!
replication, synthesis of histones, translocation of DNA polymerase into the nucleus, etc.
What is the name of the procedure when all cultured cells are brought into the same phase of the cell cycle?
synchronisation
Name two methods which are suitable for the synchronisation of a cell population!
serum starvation, mitotic shake-off, treatment with colchicine, etc.
Which method can be used to separate cells on the basis of their DNA content?
flow cytometry (FACS)
Would you name 2 mitogenic substances?
phytohaemagglutinin, PDGF, EGF, FGF, etc.
What are the components of MPF?
cyclin and cyclin dependent kinase
What kind of catalytic activity do the Cdk enzymes possess?
serine/threonine specific protein kinase activity
What are the major phases of mitosis?
prophase, metaphase, anaphase, telophase, cytokinesis
Name a protein phosphorylated by MPF!
histone H1, lamin, microtubule associated proteins, etc.
Name the four main components of the mitotic spindle!
kinetochore, polar, chromosomal and astral microtubules
Which type of microtubules is responsible for the separation and movement of chromatids?
kinetochore microtubules
Which type of microtubules is responsible for the elongation of the cell as well as for the moving off of the two poles?
polar microtubules
Name the protein complexes that hold sister chromatids together!
cohesin complexes
Name the enzyme that cleaves cohesin complexes between sister chromatids!
separase
In which phase of mitosis are the chromatids separated from each other?
anaphase
Which element of the cytoskeleton is responsible for cytokinesis?
actin filaments
What kind of cell division has a role in germ cell formation?
meiosis
What is the DNA content of those cells which are produced by meiosis?
n, haploid
What happens in the anaphase of the 1 meiotic cell division?
homologous chromosomes separate from each other
What happens in the anaphase of the 2nd meiotic cell division?
sister chromatids separate from each other
What is crossing over?
exchange of genetic material between homologous chromosomes during meiosis
What is the meaning of the semiconservative nature of replication?
one chain of the replicated DNA is the original and the other is the newly synthesized one
What is the function of template during replication?
helps nucleotide incorporation by complementary base-pairing
Why is DNA replication primer-dependent?
because DNA polymerases are unable to initiate DNA synthesis
What is the name of the continuously replicated strand of the replication fork?
leading strand
What is the name of the short DNA segments that are synthesized from the lagging template strand of the replication fork?
Okazaki-fragments
What is the name of the site where DNA replication begins?
origo (origin of replication)
Which enzyme causes relaxation of DNA during replication?
topoisomerase I
Which enzyme cleaves the hydrogen bonds at the replication fork?
helicase
What is the function of primase?
it is responsible for the synthesis of RNA primers
What is proofreading?
the removal of non-complementary nucleotides incorporated during DNA replication
What kind of enzyme activities does DNA polymerase III have?
5’→3 elongation, 3’→5 exonuclease
What kind of enzyme activities does DNA polymerase I have?
5’→3 elongation, 5’→3’ exonuclease, 3’ →5’ exonuclease
What is the function of the 3’ 5’ exonuclease activity during replication?
proofreading
What is the function of the 5’ →3 exonuclease activity during replication?
primer degradation
What is the name of the enzyme that joins the Okazaki fragments?
DNA ligase
What kind of enzyme activity does topoisomerase II have?
reversible double-stranded endonuclease
Which enzyme inhibits shortening of eukaryotic chromosomes?
telomerase
What is the enzyme activity of telomerase?
reverse transcriptase
What is the role of telomerase RNA?
template for the synthesis of telomere repeats
What is the consequence of decreasing proofreading-activity during replication?
increasing rate of mutations
What kind of DNA damage can be caused by UV irradiation?
pyrimidine dimers
Which repair system is responsible for the replacement of damaged bases?
base excision repair
Which enzyme can recognize and remove a damaged base in base excision repair?
DNA glycosylase
What is the name of the mechanism that removes pyrimidine dimers?
nucleotide excision repair
What kind of enzyme activity does the excinuclease have?
endonuclease
Name a human disease with defective nucleotide excision DNA repair!
xeroderma pigmentosum
Which repair mechanism is responsible for the correction of non-complementary basepairing?
mismatch repair
Name a human disease with defective mismatch repair!
HNPCC (hereditary non-polyposis colon carcinoma)
What are the 3 main steps of transcription?
initiation, elongation, termination
What is the name of the DNA region involved in the initiation of transcription?
promoter
What are the initial and the final sequences of a transcription unit?
initial: promoter, final: terminator
What is the name of the transcriptional step that leads to the formation of phosphodiester bonds?
elongation
What is the direction of RNA synthesis from the point of view of RNA?
5→3’
Name the RNA produced by transcription, but has not been processed yet!
primary transcript
What are the two components of the RNA polymerase in bacteria during initiation?
core enzyme and sigma factor
What is the role of the bacterial rho factor?
termination of transcription
What is the role of the bacterial sigma factor?
the initiation of transcription
Name the process by which a primary transcript is converted to a mature RNA!
RNA processing
Which enzyme produces the pre-rRNA in eukaryotic cells?
RNA polymerase I
What kind of rRNAs are produced from the mammalian pre-rRNA?
18S, 28S, 5.8S rRNA
Which rRNA is produced outside the nucleolus?
5S rRNA
What is the name of the DNA region between the 18S and 5.8S rRNA genes?
transcribed spacer
What kind of process do Christmas-trees show?
synthesis of eukaryotic rRNA
What is the role of snoRNAS?
pre-rRNA processing in eukaryotes
At which site is the maturation of ribosomal subunits finished?
cytoplasm
What is the site of the formation of ribosomal proteins?
free ribosomes of the cytoplasm
When do ribosomal subunits attach to each other?
during initiation of translation
What is the name of the pre-mRNA sequences that are absent from the mature mRNA molecules?
introns
What is the name of the pre-mRNA sequences that are present even in the mature mRNA?
exons
What is the name of the process that removes the introns from the pre-mRNA?
splicing
What are the components of the spliceosome?
pre-mRNA, snRNAs and proteins
What are the maturation processes of a pre-mRNA?
formation of the cap structure, polyadenylation, splicing
Which enzyme produces the pre-mRNAs in eukaryotic cells?
RNA polymerase II
What is the role of the mediator complex?
to connect signaling pathways to the transcriptosome
Nucleotides can be changed, added or deleted during mRNA processing. What is the name of this process?
RNA editing
What is the role of mRNA and tRNA during translation?
mRNA: template, tRNA: adapter
What kind of molecules take part in amino acid activation?
amino acid, ATP, aminoacyl-tRNA synthase
What are the products of amino acid activation?
aminoacyl-AMP, pyrophosphate
Name the molecules that are able to bind to the 3 main loops and to the 3’ end of tRNA.
ribosome, mRNA, aminoacyl-tRNA synthase, amino acid
What is a monocistronic mRNA?
it contains only one open reading frame
What is the central dogma of molecular biology?
direction of flow of information: DNA → RNA → proteins
What is a polycistronic mRNA?
It contains more than one open reading frame.
What is the start site and the end of an open reading frame?
Start: initiation codon, End: stop codon.
Which feature of the genetic code means that one amino acid could be coded by more than one codon?
Redundancy (degeneration).
Which nucleotide of a codon is involved in ‘wobble’?
The third nucleotide.
Name the enzyme that catalyzes peptide bond formation.
Peptidyl transferase.
Where can peptidyl transferase be found?
It is a ribozyme in the large subunit of the ribosome.
The anticodon of a tRNA molecule is 5’-CAU-3’, what is the sequence of the corresponding codon of mRNA (5’—3’)?
5’-AUG-3’.
Name three antibiotics able to inhibit protein synthesis.
Erithromycin, tetracycline, streptomycin, chloramphenicol.
What is the polysome made of?
A single mRNA molecule and ribosomes.
What is the direction of protein synthesis from the point of view of mRNA?
5’ → 3’.
What is the direction of protein synthesis from the point of view of protein?
N terminus - C terminus.
What are the 3 repeated steps of the elongation of translation?
Binding of aminoacyl-tRNA, peptidyl transferase reaction, translocation.
What are the sedimentation constants of the subunits and the whole ribosome in prokaryotes?
Subunits: 30S and 50S, Whole ribosome: 70S.
What are the sedimentation constants of the subunits and the whole ribosome in eukaryotes?
Subunits: 40S and 60S, Whole ribosome: 80S.
Which are the energy-dependent processes during translation?
Amino acid activation, aminoacyl-tRNA binding, translocation.
What does constitutive gene expression mean?
A certain gene is continuously expressed at the same rate.
What kind of DNA regions build up a bacterial operon?
Promoter, operator, structural genes.
What kind of an operon is the lactose operon?
Inducible operon.
What is the effect of the presence of glucose in the medium on the cAMP content of bacteria?
Decreases it.
What is the effect of the presence of glucose in the medium on the function of lactose operon of bacteria?
Decreases it.
What protein binds cAMP during the regulation of lactose operon?
CAP (catabolite activator protein).
What is the name of the DNA region in the lactose operon that binds the repressor?
Operator.
What is the role of lactose in the regulation of lactose operon?
Inducer substance.
What kind of metabolic processes are regulated by inducible operons?
Breakdown processes.
What kind of an operon is the bacterial tryptophan operon?
Repressible operon.
What is the role of tryptophan in the regulation of tryptophan operon?
Corepressor.
To what does tryptophan bind during the course of regulating the tryptophan operon?
To the repressor.
How does the presence of tryptophan affect the activity of the tryptophan operon?
decreases it
What kind of metabolic processes are regulated by repressible operons?
biosynthetic processes
Name a cis-acting regulatory element!
promoter, operator, enhancer
What is the most characteristic feature of housekeeping genes?
they are active in all types of cells
Name two levels at which gene expression can be regulated in eukaryotic cells!
transcription, RNA processing, RNA transport
Name an epigenetic mechanism of gene regulation!
histone acetylation, DNA methylation
Name a process involved in the regulation of mRNA processing!
alternative splicing, RNA editing
Give the definition of the term ‘constitutive splicing’!
the process producing a single kind of mRNA from a pre-mRNA
What are the two main mechanisms of protein breakdown in eukaryotic cells?
lysosomal digestion, ubiquitin-proteasome degradation
What is the fate of polyubiquitinated proteins in the cell?
become degraded by proteasomes
What domains of a transcription factor are absolutely necessary for its function?
DNA binding domain, activator domain
Name two groups of eukaryotic transcription factors!
helix-turn-helix, Zn-finger, amphipathic helix
Name a Zn-finger protein!
TFIIA, steroid receptors, WT-1
What is the cause of testicular feminisation?
the lack of androgen receptors
Where are glucocorticoid receptors located in a target cell not treated with glucocorticoid?
in the cytosol
Name two disorders that can be caused by malfunction of transcription factors!
cancer, endocrine diseases, developmental diseases
Name the surfaces of the endoplasmic reticulum!
cytoplasmic surface, exoplasmic surface
What kind of molecules are synthesized on the rough and on the smooth endoplasmic reticulum?
rough endoplasmic reticulum: proteins, smooth endoplasmic reticulum: lipids
What kind of proteins are synthesized on the surface of the rough endoplasmic reticulum?
secretory proteins, membrane proteins, lysosomal enzymes, proteins of the endoplasmic reticulum and the Golgi complex
On which type of ribosomes does protein synthesis start?
All proteins synthesis starts on free ribosomes
What determines whether a certain protein is synthesized on the rough endoplasmic reticulum?
the signal sequence
What is the mechanism by which the newly synthesized protein is transported into the lumen of the rough endoplasmic reticulum?
cotranslational transport
What does protein glycosylation mean?
addition of carbohydrates to a protein chain
Name a disease associated with the abnormal function of the chaperones present in the rough endoplasmic reticulum!
cystic fibrosis, familial hypercholesterolaemia
Name the two types of secretion!
constitutive and regulated secretion
Name two examples of constitutive secretion!
secretion of matrix proteins, antibodies, albumin; replacement of cell membrane components
Name two amino acids that are capable of binding to carbohydrate side chains in a protein!
asparagine, serine, threonine, hydroxylysine
Name two carbohydrates which are components of glycoproteins!
glucose, mannose, N-acetyl-glucosamine
Name the types of endocytosis (3)!
phagocytosis, pinocytosis, receptor-mediated endocytosis
In which form is cholesterol transported in the blood?
LDL particles
What kind of mechanism is used by the cells to take up LDL particles?
receptor-mediated endocytosis
What disease is caused by the absence of LDL receptors?
familial hypercholesterolaemia
Name three proteins involved in vesicular transport!
ARF, adaptin, targeting proteins, Rab proteins, chaperone proteins
Name two of the most frequently produced free radicals in the cells!
superoxide free radical, hydroxyl free radical
Which enzyme produces the superoxide free radical during phagocytosis?
NADPH oxidase
What kind of compounds are produced by the reduction of an oxygen molecule by 1, 2, 3, or 4 electrons?
superoxide free radical, hydrogen peroxide, hydroxyl free radical, water
What kind of enzymes are responsible for the inactivation of the superoxide free radical and hydrogen peroxide, respectively?
superoxide: superoxide dismutase, hydrogen peroxide: catalase, peroxidase
Free radicals degrade the unsaturated fatty acid components of the membranes. What is the name of this process?
lipid peroxidation
Name two lysosomal storage diseases!
Tay-Sachs disease, I-cell disease, Gaucher disease, Niemann-Pick disease
What kind of enzymes are present in lysosomes?
acid hydrolases
The lysosomes can digest cellular organelles. What is the name of this process?
autolysis (autophagy)
What is the signal that targets lysosomal enzymes to lysosomes?
mannose-6-phosphate
Name the three main functions of the smooth endoplasmic reticulum!
biotransformation, lipid synthesis, storage of calcium
What is the effect of phenobarbital on the cytochrome P450 system of liver cells?
induces it
List the steps of biological oxidation and their sites in the cell
Glycolysis: cytoplasm, Citric acid cycle: mitochondrial matrix, Terminal oxidation: inner membrane of mitochondrion
Biological oxidation involves the conversion of glucose to ATP through glycolysis, the citric acid cycle, and terminal oxidation.
What are the four main structural elements of a mitochondrion?
- Outer membrane
- Intermembrane space
- Inner membrane
- Mitochondrial matrix
These components play crucial roles in mitochondrial function, including energy production.
What is the cause of the different permeability of the inner and outer mitochondrial membranes?
Inner membrane: impermeable due to cardiolipin, Outer membrane: permeable due to porin
Cardiolipin is a unique phospholipid found in the inner membrane, while porins are proteins that form channels in the outer membrane.
Name the three main types of proteins of the inner mitochondrial membrane.
- Transport proteins
- Proteins of the electron transport chain
- ATP synthase
These proteins are essential for mitochondrial function and energy production.
How is pyruvate taken up by mitochondria?
By H+/pyruvate symporter
This symporter allows the transport of pyruvate into the mitochondria coupled with protons.
What is the motive force of the mitochondrial ATP synthase?
The electrochemical proton gradient
This gradient is created by the electron transport chain and drives ATP synthesis.
What are the subunits of the mitochondrial ATP synthase?
- Fo
- Fi
These subunits work together to synthesize ATP from ADP and inorganic phosphate.
Where is the site of synthesis of the proteins and RNAs of mitochondrial ribosomes?
- Proteins: on free ribosomes of the cytoplasm
- rRNAs: in the mitochondrial matrix
This separation of synthesis locations reflects the dual genetic origins of mitochondria.
How can proteins enter the mitochondrion?
By posttranslational transport
This process involves the transport of fully synthesized proteins into the mitochondria.
What is the function of chaperones in the transport of proteins into mitochondria?
They unfold the protein chain
Chaperones assist in the proper import and folding of proteins within mitochondria.
Where is the pH-value higher: in the mitochondrial matrix or in the intermembrane space?
In the mitochondrial matrix
The higher pH in the matrix is important for various mitochondrial functions, including ATP synthesis.
What is the function of the Fo component of the mitochondrial ATP synthase?
Proton channel
The Fo component facilitates the movement of protons across the inner mitochondrial membrane.
Name three disorders caused by mitochondrial DNA damage.
- Mental dementia
- Cardiomyopathy
- Optic nerve atrophy
- Glomerulopathy
Mitochondrial DNA damage can lead to a variety of diseases due to impaired energy production.
What is the name of the phenomenon where a cell contains both normal and mutated mitochondrial DNA molecules?
Heteroplasmy
Heteroplasmy can affect the severity and expression of mitochondrial diseases.
