Chapter 2

All the proteins that are expressed by a cell or organism at a given time.

mRNA carries genetic information from the nucleus to the ribosomes for protein synthesis.

A triplet is the sequence of three nucleotides in DNA coding for one amino acid.

A protein signaling molecule that regulates physiological behavior.

The 5’ end of mRNA binds to the ribosome; the start codon (AUG) is recognized; tRNA with anticodon (UAC) delivers methionine to initiate translation.

Disulphide bonds can form between cysteine amino acids to further stabilize the 3D structure.

tRNA delivers specific amino acids to the ribosome after recognizing specific nucleotide sequences on mRNA.

RNA contains ribose sugar instead of deoxyribose sugar and uses uracil instead of thymine. RNA is also single-stranded.

Transcription is the process whereby a sequence of DNA is used as a template to produce a complementary sequence of mRNA.

After pre-mRNA undergoes post-transcriptional modifications, it exits the nucleus through a nuclear pore and travels to a ribosome in the cytosol or attached to the rough endoplasmic reticulum.

Initiation, elongation, and termination.

Myosin and Actin work together to enable muscle contractions.

An operon is a cluster of linked genes that all share a common promoter and operator and are transcribed at the same time.

The sugar molecule present, the nitrogenous bases present, and whether they form single or double strands.

A codon is the sequence of three nucleotides in mRNA coding for one amino acid.

Antiparallel describes how the two strands of DNA run in opposite directions; one runs 3' to 5' and the other runs 5' to 3'.

A large molecule that is made up of small, repeated monomer subunits.

DNA consists of two polynucleotide chains that run antiparallel to each other.

Bulk transport is a type of active transport that uses vesicles to move large molecules or groups of molecules into or out of the cell.

The polypeptide chain is released by the ribosome into the cytosol or endoplasmic reticulum, where it is folded and modified into a fully functional protein.

An enzyme is an organic molecule, typically a protein, that catalyzes specific reactions.

Keratin, found in skin, hair, and nails.

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

To carry genetic information and to synthesize proteins.

The genetic code relies on the grouping of adjacent nucleotides into groups of 3.

Antibodies are involved in the immune system by recognizing and destroying pathogens.

The production of functional gene products such as proteins or non-coding strands of RNA.

Transcription and translation are allowed to proceed, facilitating increased tryptophan production.

A long chain of amino acids, also known as a protein.

The ribosome translating the mRNA reaches the attenuator sequence, which codes for two tryptophan amino acids.

They stabilize the mRNA molecule, preventing degradation and allowing it to bind to ribosomes during translation.

Initiation, elongation, and termination.

The leader region is the section of DNA just upstream of the coding region and downstream of the promoter and operator, playing a critical role in regulating gene expression.

Translation involves reading and converting the information in the mRNA molecule into a polypeptide chain.

A nucleotide includes a phosphate group, a five carbon (pentose) sugar, and a nitrogen-containing base.

Amino acids.

20 amino acids.

Different codons are made up of 3 bases and correspond to specific amino acids.

Catalase: Breaks down hydrogen peroxide into water and oxygen.

Primary, Secondary, Tertiary, and Quaternary.

The primary organelles involved in the protein secretory pathway include ribosomes, the rough endoplasmic reticulum, the Golgi apparatus, and transport and secretory vesicles.

Translation is the process where an mRNA sequence is read to produce a corresponding amino acid sequence to build a polypeptide.

RNA (Ribonucleic acid) is a single strand of nucleotides.

Hormones are chemical messengers used to communicate and induce changes in cells.

During translation, the mature mRNA is decoded and translated into a sequence of amino acids, ultimately forming a polypeptide chain.

Polypeptides

Amino acids, which have a central carbon atom, carboxyl group, amino group, an R-group, and a hydrogen atom.

Enzymes are organic catalysts that speed up chemical reactions by reducing the activation energy.

The chemical bond linking two amino acids.

Active transport is the movement of molecules across a semipermeable membrane that requires an energy input.

The mRNA molecule can be reused to produce more polypeptides.

A peptide hormone is a protein signaling molecule that regulates physiological behavior.

A structural gene is a segment of DNA that codes for proteins that play a role in the structure or function of a cell or organism.

Ribosomal RNA (rRNA) is a key structural component of ribosomes, which assemble proteins.

A phosphate group, a five-carbon sugar, and a nitrogenous base.

Insulin regulates blood sugar levels.

Acetylcholine receptors are an example of receptors.

The expression of structural genes that code for proteins involved in the production of the amino acid tryptophan.

mRNA is fed through the ribosome; codons are matched to tRNA anticodons; tRNA delivers amino acids, forming peptide bonds, and is released for the next amino acid addition.

Transcription is the process whereby a sequence of DNA is used as a template to produce a complementary sequence of mRNA.

DNA and RNA.

Amino acids are known as monomers, which join together to form polymers.

It occurs when transcription of the trp structural genes begins but is stopped early before any proteins are made.

The functional 3D shape of a protein, formed when secondary structures further fold and interact.

Transcription of structural genes necessary for tryptophan synthesis is prevented, inhibiting tryptophan synthesis and conserving energy for the cell.

The promoter is the sequence of DNA to which RNA polymerase binds.

The quaternary structure is formed when 2 or more polypeptide chains with tertiary structure join together.

A prosthetic group is a non-protein group bound to a protein, such as a vitamin or ion.

Translation is the process where an mRNA sequence is read to produce a corresponding amino acid sequence to build a polypeptide.

rRNA serves as the main structural component of ribosomes within cells.

Receptors receive signals from the environment.

RNA processing, also known as post-transcriptional modifications, involves the modification of the pre-mRNA molecule into an mRNA molecule that can be used in translation.

A molecule that is the smallest building block of a polymer.

5 carbon atoms.

Alternative splicing is the process where different exons may be spliced, resulting in a single gene producing multiple different mRNA strands.

Nucleic acids are polymers made out of nucleotide monomers.

A molecule added to the 5’ end of pre-mRNA during RNA processing.

The two strands of DNA are joined by complementary base pairs.

Non-coding regions of DNA that do not code for proteins and are spliced out during RNA processing.

Transcription of the trp structural genes is stopped to prevent unnecessary production of tryptophan.

Precursor messenger RNA (pre-mRNA) is the immediate product of transcription of a DNA sequence and requires modifications before it can undergo translation.

Transcription occurs entirely within the nucleus.

Tryptophan amino acids bound to tRNA are delivered to the ribosome and incorporated into the growing protein.

Formed when a polypeptide chain folds and coils by forming hydrogen bonds between amino acids, leading to structures like alpha-helices and beta-pleated sheets.

The mRNA dissociates from the DNA template, causing RNA polymerase to detach and halting transcription before structural genes are transcribed.

Stop codons (UAA, UAG, UGA) signal for the termination of translation.

The promoter region serves as a binding site for RNA polymerase, initiating transcription.

A common promoter sequence in eukaryotes is 'TATAAA', known as the TATA box.

The arrangement of multiple polypeptide chains.

When the operator region is not bound with a repressor protein, RNA polymerase is free to move downstream from the promoter region, allowing for the transcription of the gene.

Exocytosis is the process by which contents of a vesicle are released from a cell, allowing for the movement of large substances such as proteins out of the cell.

A chain of adenine nucleotides added to the 3’ end of pre-mRNA during RNA processing.

The fluid nature of the plasma membrane facilitates exocytosis by allowing the membrane to fuse with vesicles, making it mobile and flexible.

Translation continues until a stop codon on mRNA is reached, signaling the end of translation, and the polypeptide chain is released.

Ferritin is a protein that stores iron.

Deoxyribose.

Gene expression is the process of reading the information stored within a gene to create a functional product, typically a protein.

Support in connective tissues such as the skin.

Chains of amino acids that form proteins.

Primary, Secondary, Tertiary, and Quaternary.

The operator is a short region of DNA that interacts with repressor proteins to alter the transcription of an operon.

A protein produced by plasma cells during immune response that is specific to an antigen and combats pathogens in various ways, also known as immunoglobulin.

The antiterminator hairpin loop prevents mRNA dissociation from the template strand.

Each R group has its own chemical properties, affecting interactions between proteins.

Transcription and translation of the trp operon begin simultaneously.

Regions of DNA that code for proteins and are not spliced out during RNA processing.

It binds to the operator region of the trp operon when activated by tryptophan, blocking RNA polymerase and inhibiting transcription.

Ribose.

Transfer RNA (tRNA) recognizes specific codons on the mRNA strand and adds the corresponding amino acid to the polypeptide chain during protein synthesis.

It contains two consecutive trp codons.

RNA polymerase continues along the DNA template, allowing transcription to proceed.

An operon is a group of multiple structural genes that share a common purpose and are efficiently controlled by a single promoter and operator.

The stages of exocytosis include: 1. A vesicle containing secretory products is transported to the plasma membrane. 2. The membrane of the vesicle fuses with the plasma membrane. 3. The secretory products are released from the cell into the extracellular environment.

trpE, trpD, trpC, trpB, and trpA.

Storage proteins act as reserves for metal ions and other molecules throughout organisms.

The creation of pre-mRNA by converting genetic information from DNA into RNA.

Gene regulation is the control of gene expression, typically achieved by switching transcription on or off.

The enzyme that removes introns from the pre-mRNA molecule and joins exons together during RNA processing.

Structural genes are responsible for producing proteins involved in the structure or function of a cell, such as enzymes, transport proteins, receptors, or peptide hormones.

A repressor protein is coded for by a regulatory gene and prevents gene expression by binding to its operator.

The mRNA folds to form an antiterminator hairpin loop, preventing termination of transcription.

The operator region serves as the binding site for repressor proteins, inhibiting gene expression.

A reaction where two monomers join to form a larger molecule, producing water as a by-product.

The process where introns are cut out of a pre-mRNA molecule, and exons are joined together.

Transcription of the trp structural genes is started to increase the amount of tryptophan available.

Messenger RNA (mRNA) carries genetic information from the nucleus to the ribosomes and is produced during transcription.

Amino acids join together at a cell's ribosomes via a condensation reaction, forming peptide bonds between adjacent amino acids.

A terminator hairpin loop forms in the mRNA due to specific folding via hydrogen bonds.

The start codon AUG codes for the amino acid methionine.

Transcription ends at the termination sequence, RNA polymerase detaches, and pre-mRNA is released.

The chain of amino acids.

Regulatory proteins can turn gene expression off or on and can increase or decrease the rate of gene expression by promoting or hindering transcription.

Transcription, RNA processing, and Translation.

Trp operon attenuation stops transcription by prematurely ceasing translation.

They control the entry and exit of substances from a cell.

The sequence of amino acids in a polypeptide chain.

They fold and modify each polypeptide chain into a fully functional protein, which can either remain in the cell or be exported out via exocytosis.

At the end of the leader region of the trp operon.

Structural genes are often found downstream (towards the 3’ end) of the regulatory gene that controls them.

An activator protein is coded for by a regulatory gene and increases gene expression.

Regulatory genes code for proteins that influence the expression of structural genes.

A regulatory gene produces proteins that control the expression of other genes.

An enzyme is an organic molecule, typically a protein, that catalyzes (speeds up) specific reactions.

Pre-mRNA is processed into mRNA, which carries the message for protein synthesis to the ribosomes.

Alpha helix and beta sheet.

The trp operon contains genes involved in the production of the amino acid tryptophan, which can be used in protein production.

Transcription factors bind to the promoter region, RNA polymerase binds, and DNA strands unwind.

The bonding of multiple polypeptide chains together.

Continued transcription and translation occur, allowing for the synthesis of proteins even in low tryptophan conditions.

Different cells express different genes to produce appropriate proteins for their specific functions, such as skin cells producing different proteins than heart cells.

RNA polymerase moves along the DNA template, adding complementary RNA nucleotides to form pre-mRNA.

The ribosome pauses because there is no tRNA-bound tryptophan in the cell.

Activator proteins initiate or increase the expression of structural genes.

The 3D structure of the protein.

The termination sequence signals for the end of transcription.

Repressor proteins inhibit or decrease the expression of structural genes.

Introns are regions of non-coding DNA that do not contribute to the final protein and are removed during RNA processing.

When the operator region is bound with a repressor protein, RNA polymerase cannot move downstream from the promoter region, inhibiting transcription of the gene.

Exons are regions of coding DNA that are transcribed and translated into the final protein.