Cell Bio Exam 2

3 steps of translation process

1. Initiation 2. Elongation 3. Termination

mRNA, tRNA, rRNA

3 major types of RNA

Glycocalyx

A carbohydrate-rich layer made of the ogliosaccharides attached to membrane glycolipids and glycoproteins. Always on external surface of the cell mebrsine. Modulated adhesion between cells and cell surface characteristics.

lipid bilayer

A continuous _____ provided a basic structure and serves as a semipermeable barrier. Form the basic skeletal structure of membranes.

separate different types of cells

A fluorescence-activated cell sorter (FACS) is most useful to

facilitated diffusion

A form of passive movement of molecules along their concentration gradient with the help of a channel protein

Stop codon

A gene typically includes following elements except Promoter Coding region Terminator Stop codon

cell fractionation

A lab technique to separate organelle of the cell.

the neuron expresses some mRNAs that the white blood cell does not.

A neuron and a white blood cell have very different functions. For example, a neuron can receive and respond to electrical signals, while a white blood cell defends the body against infection. This is because

3' UCA 5'

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

release factor

A protein that binds to the A site and causes termination of translation by recognizing stop codon in an mRNA sequence

A protein that causes termination of translation

A release factor is

large; small

A ribosome contains a ______ (60S) and a _____ subunit (40S)

Ribozyme

A small RNA with catalytic activity

start codon

AUG, which encodes methionine, is used to initiate protein synthesis. It is called a ______

protein

According to the fluid mosaic model of cell membranes, which type of molecule spans the membrane, from its inner to outer surface?

embedded in a lipid bilayer

According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly

attachment of amino acids to tRNAs.

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the

3' poly(A) adenlyation

Addition if 100-250 adenylates (A) at 3' end.

5' capping

Addition of a methylated guanylate (G) at 5' end.

somatic cells

All _____ ____ have the same DNA in an organism, but expression of a specific set of genes in a cell determines it's unique structure and specific function.

Removes all introns and rejoins exons in different combinations to create mRNAs with different functions

Alternative RNA splicing

Immunocytochemistry

Antibody based fluorescence microscopy

No

Are all DNA sequence transcribed into RNA?

Cell lines

Are cultured of animal cells that can be propagated repeatedly and sometimes indefinitely. Can be derived from genetically modified (mutated m) and transformed cells (immortalized cells) such as cancer cells

Aquaporins

Are membrane water channels that play critical roles in controlling the water contents of cells. Are found in the cell membrane of certain cells, such as epithelial cells of the kidney where large amount of water exchange takes place. Usually form tetramers, with each monies defining a single channel.

Peripheral proteins

Associate with the membrane by interaction with integral proteins or hydrophilic heads of lipids. Can be localized at either side of the bilayer

one

Bacteria and archaea only have _____ RNA polymerase

Phalloidin

Binds specifically at the interface between subunits of actinfilaments looking adjacent subunits together.

tRNA

Bring specific amino acids to their right positions during translation. There are 30-40 different tRNA. therefore an amino acid may have more than one.

mRNA

Carries genetic information copied from DNA in the form of a 3-nucleotide sequences

tRNA synthetase

Catalyzes the attachment of amino acids to tRNA, specifically recognizes an amino acid and it's compatible tRNA

interactions with other cell types as in a whole organism are lost

Cell culture is in vitro study because

A lab technique to break cells and separate organelles

Cell fractionation is

The bleached molecules would diffuse laterally through the membrane and intermix with unbleached molecules

Cell surface molecules are labeled with a fluorescent tag and then a portion of them are bleached with a laser beam. What would one observe after the cell is incubated for a few minutes?

Primary cells

Cells isolated from normal tissues. They can grow in a culture dish for several generations, but they have limited life span.

charge

Centrifugation is a laboratory technique to separate organelles of the cell based on the following properties except

amphipathic

Cholesterol is an essential component of biological membranes. Although it is much smaller than the typical phospholipids and glycolipids in the membrane, it is a/an____________ molecule.

in the interior of the membrane

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?

Cholesterol

Contains rings of hydrocarbon structures in its hydrophobic part and a hydroxyl group as it's part

nucleus

DAPI (4',6-diamidino-2-phenylindole) is a chemical compound that emits blue fluorescence. It is used extensively in fluorescence microscopy to identify

Transcription factors

DNA binding proteins that regulate transcription process (in eukaryotes)

Centrifugation

Different organelles with different physical properties (size, shape, density) will settle down at different rates from a suspension when centrifuged

Codon

Each group of 3 consecutive nucleotides in mRNA is call a _____

anti-codon

Each tRNA recognizes the codon in mRNA through its ______

Primary cells

Endothelial cells isolated from normal umbilical cords have limited life span in culture. They are

three

Eukaryotic cells have ____ different RNA polymerase which produce different types of RNA (pol I, pol II, and pol III)

Alternative RNA splicing

Exons of a gene can be arranged in different combinations. A mechanism by which different forms of mRNAs are generated from the same pre-mRNA. Biological significance- leading to the production of more than one related proteins, or isoforms from the same gene.

in vivo

Experiments conducted in living organisms (such as drug testing in clinical trials)

In vitro

Experiments performed with cellular structures or tissues isolated from living organisms (most lab studies)

small interference RNA (siRNA)

Foreign double-stranded RNA (such as viral RNA )are cut into ______. Derived from pathogenic RNA and used against pathogens.

the small subunit of ribosome is assembled at the start codon AUG of mRNA with the initiator tRNA, Met-tRNA.

From the following list, which is the first event in translation in eukaryotes

transcription

Gene expression is primarily regulated at the level of

Introns are removed from RNA molecules by the spliceosome, which works in the nucleus.

Genes in eukaryotic cells often have intronic sequences coded for within the DNA. These sequences are ultimately not translated into proteins. Why?

Attach it to another cellular protein as a fluorescence marker, enabling scientists to localize the protein in the cell.

Green fluorescent protein (GFP) is a protein in the jellyfish Aequorea Victoria that exhibits green fluorescence when exposed to light. Biologists often use GFP for which of following:

Phospholipids

Have a phosphate group in their hydrophilic head. They are the most abundant membrane lipids.

Glycolipids

Have a sugar group in their hydrophilic head. They are found on the surface of all plasma membranes.

are a cell line are transformed are immortalized

HeLa cells are tumor cells derived from cervical cancer tissue and used in medical research. They have been cultured for numerous generations since their isolation in 1952, therefore, HeLa cells

none of the above

How is the head and the tail part WITHIN a phospholipid molecule held together? non-covalent interaction hydrophobic interaction ionic interaction

950 bp

If a gene produces a pre-RNA that is 1200 base pairs long and has the following intron-exon structure: exon 1 (200bp) intron (100bp) exon 2 (50bp) intron 2 (150bp) exon 3 (700bp). How many base pairs long would we except the mRNA to be?

Serum

In cell culture, the growth factors and hormones essential for cell growth are provided by

RNA polymerase II

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?

All of the choices are correct

In eukaryotic cells, internal membranes contain proteins essential for the function of different organelles form membranous compartments called organelles provide additional area where many metabolic processes occur

RNA processing

In eukaryotic cells, the primary RNA transcripts undergo several modifications in the nucleus to produce functional RNA, the process known as ________

transmission electron microscopy.

In order to visualize the fine structure of viruses and cytoskeletal filaments at 10-25 nanometers in diameter the type of microscopy that would be ideal is

As soon as transcription has begun

In prokaryotic cells, translation begins

Certain proteins are unique to each membrane.

In what way do the membranes of a eukaryotic cell vary?

Fluorescence-activated cell sorter (FACS)

Instrument that is very powerful to separate different cells in suspension

their presence allows exons to be alternatively spliced

Introns are significant to biological evolution because

TATA-binding protein (TBP)

Is a transcription factor. It recognizes and bunds to the TATA box sequence of the promoter, and helps to initiate transcription process.

gene expression

Is the process by which the genetic information encoded in DNA is translated into protein sequence. It includes transcription and translation. A complex process regulated at multiple levels and by many factors.

template strand (noncoding strand or antisense strand)

Is the strand used by RNA polymerase to attach complementary bases during transcription

lipid-anchored proteins

Linked to one or more lipid molecules through different covalent bonds. Protein itself does not enter into the bilayer

proteins located on the surface of the cell membrane that are covalently attached to membrane lipids

Lipid-anchored proteins (also known as lipid-linked proteins) are

discontinuous

Many eukaryotic genes are ______. (Interrupted by noncoding sequences, introns.)

Gyloproteins

Many membrane proteins are glycosylated

TATA box

Most eukaryotic promoters contain a DNA sequence called the _____. Which is recognized by the TATA binding protein (TBP)

Fluorescence microscope

Most useful to localize a specific protein or a structure in the cell. Similar to light microscope in magnification and resolution

Active transport

Move a solute against its concentration gradient that requires energy

Passive transport

Move a solute along its concentration gradient without the need of energy input.

secondary active transport

Na+/glucose transporter uses energy released by movement of Na+ down its concentration gradient to power the movement of glucose against its concentration gradient

Redundant

One amino acid can be coded for by more than one codon, which reduces the risk of mutations

You forgot to add penicillin and streptomycin to your media

One of your dishes of mammalian cells has bacterial contamination! What is the most likely reason?

Template

One strand of the DNA double helix is used as a ______ to determine the nucleotide sequence of RNA.

Actinfilaments

Phalloidin belongs to a class of toxins called phallotoxins, which are found in the death cap mushroom. It is a rigid bicyclic heptapeptide that is lethal after a few days when injected into the bloodstream. Phalloidin containing fluorescent tags are used widely in microscopy to visualize

Functions of 5' cap and 3' poly (A) tail

Protects mRNA from enzymatic degradation. Assists export of mRNA from the nucleus to the cytoplasm Assists in translation.

Green Fluorescent Protein (GFP)

Protein expressed in jellyfish that exhibits green fluorescence. Can be fused with a cellular protein gene and used as a reporter to localize the protein in the cell.

1. The sugar part in nucleotides is ribose 2. The base T (thymine) in nucleotides of DNA is replaced by U (uracil) in RNA

RNA differs from DNA in 2 ways:

it is single-stranded and can fold up into a variety of structures

RNA in cells differs from DNA in that

single-stranded

RNA is ________ and can fold into different shapes.

5' to 3'

RNA is synthesized from _____.

3' to 5'

RNA polymerase always loves in the ______ direction with respect to the template DNA strand.

3"—>5" along the template strand

RNA polymerase moves in which direction along the DNA?

3' → 5' along the template strand

RNA polymerase moves in which direction along the DNA?

spliceosome

RNA splicing is catalyzed by a ______, a large complex of proteins and a small nuclear RNA or a ribozyme

elongation

RNApol advances down the template from 3' to 5'

Assembly

RNApol recognizes the promoter region

Termination

RNApol releases once the terminator sequence is reached. RNApol can restart another round of transcription

Reading frames

Refer to the three possible ways of reading the 3-nucleotide codons in DNA or RNA

Promoter

Regulatory region of DNA located upstream of a gene. It is an initiation point for gene expression.

RNA splicing

Ribozymes are known to catalyze which of the following reactions in cells?

High levels of unsaturated fatty acyl tails within the lipid bilayer

Scientists unearth a Wooly Mammoth from the Siberian Ice Sheath and discover that a eukaryotic "amoeba"-like cell is still alive. Which component of the cell membrane might contribute to maintaining the fluidity of plasma membranes under freezing conditions

K+ channels

Selectively let K+, not other ions, pass through the channel.

Primary cells

Smooth muscle cells isolated from a blood vessel can only grow for several generations in culture. They are

Nucleolus

Synthesis of pre-rRNA occurs in the

wobble position

The 3rd base of a codon can form a nonstandard base pair with an anti-codon therefore it is called a _____

is a transcription factor that specifically binds to the promoter region

The TATA-binding protein

Amphipathic nature

The _____ of phospholipids makes them spontaneously form a lipid bilayer in acqueous environment, which is the molecular basis for the assembly of biomembranes

Base pairing rule

The addition of a nucleotide to the elongating RNA strand is determined by the specific nucleotide at the template according to the ____

to make proteins in specific cell types to make proteins at specific stages of development to respond to environmental changes

The cell has highly regulated mechanisms to control gene expression. A reason for gene regulation is

Polyribosome

The complex of several ribosomes and a mRNA engaged in translation

transcription of genes transcribed by RNA polymerase II.

The distinct characteristics of different cell types in a multicellular organism result mainly from the differential regulation of the

peptidyl transferase

The enzyme catalyzing peptide bond formation is

peptidyltransferase

The enzyme that catalyzes peptide bond formation. It is an RNA enzyme in the large subunit of the ribosome

RNA polymerase

The enzyme that catalyzes the polymerization reaction (catalyzes RNA synthesis)

Central Dogma

The flow of genetic information in all living cells from DNA to RNA to protein.

a carbohydrate coat covering the cell

The glycocalyx is

400x

The magnification of a specimen viewed with a 10x eyepiece and 40x objective lens is

Resolution

The minimal distance of two points can be distinguished. It is a measurement of clarity

Fluid mosaic model

The model that describes the structure of cell membranes. Fluid- membrane components are mobile. Mosasic- proteins and lipids are asymmetrically distributed in the lipid bilayer

Chromatin remodeling

The physical structure of DNA, in the form of chromosome or chromatin (_________), can affect the access of transcription factors and RNA polymerases to specific genes.

RNA splicing

The process of removing introns from pre-mRNA and joining exons.

simultaneously

The processes of transcription and translation occur ______ in prokaryotic cells. Transcribed mRNA, tRNA, and rRNA can be immediately used for protein synthesis without further modification.

The enzyme that catalyzes peptide bond formation is a ribosomal RNA

The ribosome is important for catalyzing the formation of peptide bonds. Which of the following statements is TRUE?

is a subunit of RNA polymerase that specifically binds to the promoter and initiates transcription

The sigma factor in bacterial RNA polymerase

recognizes promoter sites in the DNA.

The sigma subunit of bacterial RNA polymerase

the minimal distance of two points can be distinguished

The term "resolution" describing a microscope refers to which of the following

the rules for base pairing between the third base of a codon and tRNA are flexible.

There are 61 mRNA codons that specify amino acids, but only 45 tRNAs. This is best explained by the fact that

The third bass of the codon is a wobble position

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that

fluorescence microscopy

To localize an ion channel protein in the cell membrane, you would use

mRNA

Total nucleic acids are extracted from a culture of yeast cells and are then mixed with resin beads to which the polynucleotide 5′-TTTTTTTTTTTTTTTTTTTTTTTTT-3′ has been covalently attached. After a short incubation, the beads are then extracted from the mixture. When you analyze the cellular nucleic acids that have stuck to the beads, which of the following is most abundant?

transcription factors

Transcription in eukaryotes requires which of the following in addition to RNA polymerase

Transcription factors

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

both follow base-pair rule during synthesis

Transcription is similar to DNA replication in that

Nucleolus

Transcription of pre-rRNA takes place in the _____

Initiation

Transcription starts using one of the DNA strand as the template (the bottom strand)

one DNA strand

Transcription uses _______ as the template. Some genes are transcribed using this, whereas others are transcribed using the other DNA strand.

transmission electron microscopy shows two-dimensional ultrastructure, while the scanning electron microscopy shows three-dimensional structure

Transmission and scanning electron microscopy differ mainly because

ATP pumps

Transport against concentration gradient Use the energy form hydrolysis of ATP different pumps transport different ions or small molecules

Channels

Transport down concentration or electric gradient Form a hydrophilic passage Transport ions, H2O or small hydrophilic molecules

antiporters

Transport two types of molecules to opposite direction

Symporters

Transport two types of molecules to same direction

Osmosis

Transportation of water across a semi-permeable membrane from a solution of low solute (hypotonic) to a solution of high solute (hypertonic) until solute concentrations are equal (isotonic)

stop codons

UAA, UGA, and UAG do not encode amino acids. Protein synthesis is terminated at these codons, they are called ______

RNA allow for the formation of polyribosomes, increasing the efficiency of protein synthesis.

Using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because

RNA can be modified in multiple ways for the regulation of gene expression

Using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because

groups of ribosomes reading a single mRNA simultaneously

What are polyribosomes

Clusters of ribosomes linked together by a mRNA molecule that are engaged in protein synthesis

What are polysomes?

exons

What are the coding segments of a stretch of eukaryotic DNA called?

the nucleotide sequence of the template strand

What determines the nucleotide sequence of the newly synthesized RNA?

an RNA with enzymatic activity

What is a ribozyme?

It is the movement of lipids and integral proteins within the lipid bilayer

What is meant by the term "fluid mosaic model"?

It allows cellular components, such as organelles, to be studied in isolation

What is the purpose for the use of cell fractionation in cell biology?

Recruit RNA polymerase and transcription factors to DNA

What is the role of the promoter region in the regulation of gene expression

as soon as transcription has begun

When does translation begin in prokaryotic cells?

All integral membrane proteins contain hydrophobic regions.

Which is a property of integral membrane proteins

Transmembrane proteins

Which membrane component is most important for allowing large, charged molecules to pass through the membrane?

small RNA

Which of the following RNA serves the regulatory functions including splicing and gene expression?

The ribosome binds to the mRNA

Which of the following does not occur before a eukaryotic mRNA is exported from the nucleus?

the action of protein that blocks TATA box binding protein function

Which of the following examples does NOT describe a mechanism of post-transcriptional control of gene expression?

selective permeability

Which of the following functions of the plasma membrane is possible without membrane proteins?

5' cap and poly (A) tail

Which of the following help(s) to stabilize mRNA by inhibiting its degradation?

starch

Which of the following is NOT the part of culture medium for animal culture?

The membrane reseals

Which of the following is most likely to occur after the lipid bilayer is pierced?

fluorescence microscopy

Which of the following is the best choice to localize a histone protein in the nucleus with its antibody?

transmission electron microscopy

Which of the following is the best choice to study the detailed internal structures of nucleolus?

cholesterol

Which of the following membrane lipids does not contain a fatty acid tail

all of the above

Which of the following methods are used by cells to regulate the activity or amount of a protein in the cell? Alternative splicing Protein phosphorylation/dephosphorylation Translation by polysomes

Nuclear pore complexes can regulate the speed at which newly synthesized proteins are exported from the nucleus into the cytoplasm

Which of the following methods is not used by cells to regulate the amount of a protein in the cell?

different copies DNA can be replicated according to different physiological processes

Which of the following methods is not used by cells to regulate the amount of a protein in the cell?

a mutation that introduced extensive sequence changes into the DNA that precedes the gene's transcription start site

Which of the following might decrease the transcription of only one specific gene in a bacterial cell?

5′-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3′

Which of the following molecules of RNA would you predict to be the most likely to fold into a specific structure as a result of intramolecular base-pairing?

destroys double-stranded viral RNA as a cellular defense system

Which of the following statements about RNAi is true?

miRNAs are produced from rRNAs.

Which of the following statements about miRNAs is FALSE?

Ribosomes must bind to the 5′ cap before initiating translation

Which of the following statements about prokaryotic mRNA molecules is FALSE

AUG serves as start codon in all mRNAs

Which of the following statements about the genetic code is CORRECT?

The genetic code is redundant.

Which of the following statements about the genetic code is CORRECT?

Membrane carbohydrates function primarily in cell-cell recognition

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?

The only known function of RNA molecules is their involvement in translation

Which of the following statements is FALSE?

Membrane lipids frequently diffuse within the plane of the membrane

Which of the following statements is TRUE

A ribosome is a large rRNA and protein complex

Which of the following statements is TRUE?

a deletion of 2 nucleotides

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of transla-tion, is likely to have the most serious effect on the polypeptide product?

phospholipids

Which type of lipids are the most abundant in the plasma membrane

The nucleus labeled with DAPI

With a fluorescence microscope, you can detect

the nucleus

With a light microscope, it is likely that you can see

Nearly universal

With the only rare exceptions, codons are the same among plants, animals, bacteria, and fungi

5′-AUAGGCAUUCGAUCCGGAUAGCAU-3

You have a piece of DNA that includes the following sequence: 5′-ATAGGCATTCGATCCGGATAGCAT-3′ 3′-TATCCGTAAGCTAGGCCTATCGTA-5′ Which of the following RNA molecules could be transcribed from this piece of DNA?

Genes; gene

____ provide the instruction for making proteins, but a ____ is not directly used to build a protein

transcription; translation

_____ and _____ are the 2 processes that transmit the genetic information from a gene to a protein.

All cells

_______, from bacteria to human, follow the same principle. (The central dogma)

Exon

a segment of a DNA or RNA molecule containing information coding for a protein or RNA.

Intron

a segment of a DNA or RNA molecule that does not code for proteins or RNA.

The TATA box

acts to position RNA polymerase for transcription initiation

Genes transcribed by RNA polymerase II

all protein-coding genes, miRNA genes, plus genes for some small RNAs

What is a ribozyme

an RNA with enzymatic activity

Function of mRNA

code for proteins

DAPI

emits blue fluorescence after it binds to DNA

Function of rRNA

form the core of the ribosome and catalyze protein synthesis

Sigma factor

is a subunit of RNA pol that specifically binds to the promoter and initiates transcription in bacteria.

Genes transcribed by RNA polymerase I

most rRNA genes

Monomers

nucleotides: ATP, GTP, UTP, and CTP

Mammalian

rRNA is most abundant in ______ cells.

Function of miRNA

regulate gene expression

tRNA synthesis and Processing

removing the 5' end sequence adding CCA sequence to 3' end modification of bases resulting in non-conventional bases (D,I) removing introns in some tRNA

Coding strand

sense strand

Function of tRNA

serve as adaptors between mRNA and amino acids during protein synthesis

Coupled transporters

symporters and antiporters are _______

Genes transcribed by RNA polymerase III

tRNA genes, 5S rRNA genes, genes for many other small RNAs

Magnification

the ratio of an object's image to its real size

miRNA

transcribed as pro-microRNA in the nucleus and processed to miRNA. A class of short 22 nucleotide sequences that bind to complementary sequences in the sequence of target mRNA, usually resulting in their destruction of target MRA, inhibiting gene expression

Uniporters

transport a single type of molecule

Function of other small RNAs

used in RNA splicing, telomere maintenance, and many other processes