Biochemistry Chapter on Lipids and Reactions

Questions and Answers

What are unsaturated fatty acids?

Liquid at room temperature (correct)

Solid at room temperature

Not saturated with hydrogen bonds (correct)

Have double bonds in carbon chain (correct)

What is the major function of fats?

Storing energy

Which statement describes phospholipids?

Two hydrophilic fatty acid tails

Hydrophobic phosphate head

Major components of cell membranes (correct)

Forms a phospholipid monolayer

What do anabolic reactions involve?

Construction of complex molecules Signup and view all the answers

What are catabolic reactions characterized by?

The release of energy Signup and view all the answers

What are nucleic acids made of?

Polymers of nucleotide monomers Signup and view all the answers

What is the primary function of nucleic acids?

Store and transmit hereditary information Signup and view all the answers

Which of the following are types of nucleic acids?

Ribonucleic acid (RNA) Signup and view all the answers

What is the main function of DNA?

Store information, direct RNA synthesis and control protein synthesis Signup and view all the answers

What is the main function of RNA?

Translate DNA into polypeptides Signup and view all the answers

What are nucleotides composed of?

Nitrogenous base Signup and view all the answers

A nucleoside contains a phosphate group.

False Signup and view all the answers

What is a phosphodiester bond?

Binds nucleotides together to form polynucleotides Signup and view all the answers

Which of the following describe pyrimidines?

Nucleotides with one ring structure Signup and view all the answers

Which describe purines?

Nucleotides with two ring structures Signup and view all the answers

RNA is usually double stranded.

False Signup and view all the answers

How is DNA structured?

Forms hydrogen bonds between base pairs Signup and view all the answers

What are the complementary base pairing rules in DNA?

Cytosine with Guanine, Thymine with Adenine Signup and view all the answers

What happens during transcription?

Information from DNA is transferred to messenger RNA Signup and view all the answers

What is translation?

Ribosomal complex attaches to mRNA to form a polypeptide Signup and view all the answers

What is the central dogma of molecular biology?

DNA transcribed into RNA, which is translated into proteins Signup and view all the answers

What are proteins composed of?

Polymers of amino acids Signup and view all the answers

Which of the following best describes amino acids?

All of the above Signup and view all the answers

What are peptides?

Both A and C Signup and view all the answers

Polar amino acids have nonpolar side chains.

False Signup and view all the answers

What is the role of cysteine in proteins?

Forms disulfide bridges to determine protein folding Signup and view all the answers

What is unique about glycine?

Single hydrogen atom in the side chain Signup and view all the answers

What distinguishes proline from other amino acids?

Ring structure Signup and view all the answers

What are peptide bonds?

Covalent bonds between amino acids Signup and view all the answers

What defines the primary structure of a protein?

Amino acid sequence Signup and view all the answers

What is secondary structure in proteins?

Alpha helices and beta-pleated sheets Signup and view all the answers

What is tertiary structure in proteins?

Bonds between variable groups of amino acids Signup and view all the answers

What characterizes quaternary structure of proteins?

Combination of multiple polypeptides Signup and view all the answers

What is a key feature of enzymes?

Not altered permanently Signup and view all the answers

What are ribozymes?

Catalytic RNA molecules Signup and view all the answers

What is the active site of an enzyme?

Area where substrates are held Signup and view all the answers

What is a substrate in enzymatic reactions?

The reactant that binds to an enzyme Signup and view all the answers

What is an enzyme-substrate complex?

Formed when substrates bind to the active site Signup and view all the answers

What is induced fit in enzyme activity?

Enzyme shape changes to fit the substrate Signup and view all the answers

What are cofactors?

Nonprotein organic compounds/inorganic ions Signup and view all the answers

What are prosthetic groups?

Non-amino acid groups permanently attached to enzymes Signup and view all the answers

What are coenzymes?

Organic molecules that assist enzymes Signup and view all the answers

What is a metabolic pathway?

Step-by-step enzyme-mediated process Signup and view all the answers

What are enzyme inhibitors?

Substances that stop enzyme activity Signup and view all the answers

What describes irreversible inhibition?

Prevents substrate binding Signup and view all the answers

What characterizes competitive inhibitors?

Both A and B Signup and view all the answers

How do noncompetitive inhibitors work?

Change enzyme shape Signup and view all the answers

What is allosteric regulation?

Changing enzyme activity through binding elsewhere Signup and view all the answers

What are allosteric activators?

Molecules that enhance enzyme activity Signup and view all the answers

What do allosteric inhibitors do?

Inhibit enzyme activity Signup and view all the answers

What role do protein kinases serve?

Add phosphate groups to proteins Signup and view all the answers

What do protein phosphatases do?

Remove phosphate groups Signup and view all the answers

What is feedback inhibition?

End product inhibits first enzyme in pathway Signup and view all the answers

What is the commitment step in a metabolic pathway?

First reaction in the pathway that is regulated Signup and view all the answers

What are isozymes?

Enzymes that catalyze the same reactions but different properties Signup and view all the answers

What is the cell theory?

Cells are the smallest functional unit of life Signup and view all the answers

What is the plasma membrane?

Selectively permeable Signup and view all the answers

What do both prokaryotic and eukaryotic cells have?

Ribosomes Signup and view all the answers

What does describe prokaryotic cells?

One circular chromosome Signup and view all the answers

What describes eukaryotic cells?

Double nuclear membrane Signup and view all the answers

What are the three major parts of eukaryotic cells?

Cytoplasm Signup and view all the answers

What occurs in the nucleus?

DNA replication and transcription Signup and view all the answers

What are chromosomes made of?

Proteins Signup and view all the answers

What is the nuclear envelope?

Double membrane surrounding the nucleus Signup and view all the answers

What is the function of the nucleolus?

Production of ribosomal RNA (rRNA) Signup and view all the answers

What are ribosomes made of?

rRNA and protein complex Signup and view all the answers

What is the cytoplasm?

Everything within the cell except the nucleus Signup and view all the answers

What is the endomembrane system?

Regulates protein traffic in the cell Signup and view all the answers

What does the rough ER do?

Studded with ribosomes, synthesizes proteins Signup and view all the answers

What is the function of smooth ER?

Synthesizes lipids and detoxifies molecules Signup and view all the answers

What is the Golgi apparatus's function?

Modifies and ships products from the ER Signup and view all the answers

What do lysosomes do?

Break down large molecules Signup and view all the answers

What is phagocytosis?

Cells engulf material forming phagosomes Signup and view all the answers

What characterizes primary lysosomes?

Arise from the Golgi apparatus Signup and view all the answers

What defines a secondary lysosome?

Formed when primary lysosomes fuse with phagosomes Signup and view all the answers

What is autophagy?

Destruction of old cell parts by lysosomes Signup and view all the answers

What organelles are not part of the endomembrane system?

Mitochondria Signup and view all the answers

What is the main function of mitochondria?

Powerhouse of the cell Signup and view all the answers

Which is a function of chloroplasts?

Photosynthesis Signup and view all the answers

What is chlorophyll?

Photosynthetic pigment in plants Signup and view all the answers

What are thylakoids?

Sacs that form stacks in chloroplasts Signup and view all the answers

What is stroma?

Fluid outside thylakoid membranes in chloroplasts Signup and view all the answers

What similarities exist between mitochondria and chloroplasts?

Double membranes Signup and view all the answers

What are peroxisomes?

Organelles that break down toxic by-products Signup and view all the answers

What are glyoxysomes?

Organelles converting stored lipids to carbohydrates in plants Signup and view all the answers

What are vacuoles?

Increase cell size with water Signup and view all the answers

What makes up the cytoskeleton?

All of the above Signup and view all the answers

What are microfilaments made of?

Actin protein Signup and view all the answers

What is the role of intermediate filaments?

Anchor the nucleus and organelles Signup and view all the answers

What are microtubules?

Hollow tubes made of tubulin Signup and view all the answers

What are cilia?

Hair-like structures made from microtubules Signup and view all the answers

What characterizes flagella?

Longer than cilia and move in a snake-like motion Signup and view all the answers

What do cell walls do in plants?

Maintain shape and volume Signup and view all the answers

What is the extracellular matrix?

Gel-like matrix of glycoproteins Signup and view all the answers

What are cell junctions?

Connections formed between adjacent cells Signup and view all the answers

What are plasmodesmata?

Connections in plant cells allowing cytoplasm flow Signup and view all the answers

What are tight junctions?

Seal off adjoining animal cells Signup and view all the answers

What are desmosomes?

Affix cells into strong sheets Signup and view all the answers

Study Notes

Unsaturated Fatty Acids

Not saturated with hydrogen, characterized by double bonds or kinks in the carbon chain.
Remain liquid at room temperature, important for cell membrane fluidity.

Fat Function

Major role is energy storage within organisms.

Phospholipids

Composed of a hydrophilic phosphate head and two hydrophobic fatty acid tails.
Essential components of cell membranes, forming a bilayer that arranges with hydrophilic heads facing outward and hydrophobic tails inward.

Anabolic Reactions

Involve the synthesis of complex molecules from simpler ones; require energy input.
Considered endergonic reactions, where the free energy of products exceeds that of the reactants.

Catabolic Reactions

Break down complex molecules into simpler ones, releasing energy.
Classified as exergonic reactions, where the free energy of products is less than that of reactants.

Nucleic Acids

Polymers made up of nucleotide monomers, crucial for storing and transmitting genetic information.

Function of Nucleic Acids

Store, transmit, and utilize hereditary information through genes.

Major Nucleic Acid Types

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

DNA Functions

Stores genetic information, directs RNA synthesis, and controls protein synthesis.

RNA Functions

Translates DNA sequences into polypeptides (proteins).

Nucleotide Structure

Comprised of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Nucleoside Structure

Consists of a pentose sugar and a nitrogenous base.

Phosphodiester Bond

Links nucleotides through a condensation reaction; connects the hydroxyl group on the 3' carbon of one nucleotide to the phosphate group on the 5' carbon of another, forming the backbone of polynucleotides.

Pyrimidines and Purines

Pyrimidines: single-ringed nucleotides (Cytosine, Thymine/Uracil in RNA).
Purines: double-ringed nucleotides (Adenine, Guanine).

RNA Structure

Typically single-stranded; can fold back on itself through hydrogen bonding.

DNA Structure

Double helix structure, with hydrogen bonds forming between complementary bases (A-T and C-G pairing).

Base Pairing Rules

DNA: C pairs with G, T pairs with A; RNA: C pairs with G, U pairs with A.
C-G bonds are stronger than A-T bonds.

Transcription

The process of transferring genetic information from DNA to messenger RNA (mRNA) within the nucleus.

Translation

Involves the formation of a polypeptide (protein) where a ribosomal complex interprets mRNA.

Central Dogma

Describes the flow of genetic information: DNA → RNA → Protein.

Proteins

Polymers of amino acids, perform multiple roles including enzymatic activities, defense, regulation, and transport.

Amino Acids

Composed of 20 common types; consist of an amino group, carboxyl group, and a variable side chain (R group).

Peptides

Short chains of amino acids (20 or fewer), often act as signaling molecules or hormones.

Polar and Nonpolar Amino Acids

Polar amino acids have hydrophilic side chains.
Nonpolar amino acids are hydrophobic with nonpolar side chains.

Cysteine, Glycine, Proline

Cysteine: Contains thiol groups, forms disulfide bridges, influencing protein folding.
Glycine: Smallest amino acid, fits into tight spaces in proteins.
Proline: Contains a ring structure, affecting protein geometry.

Peptide Bonds

Covalent bonds formed between amino acids during dehydration synthesis; growth occurs from the amino terminus to the carboxyl terminus.

Protein Structures

Primary: Sequence of amino acids.
Secondary: Local folding patterns like α-helices and β-pleated sheets.
Tertiary: Overall 3D structure formed by interactions between R-groups.
Quaternary: Arrangement of multiple polypeptides into functional units.

Enzymes

Specialized proteins that catalyze reactions without being consumed; commonly end in -ase.

Active Site and Substrate

Active site: Area on enzyme where substrates bind specifically.
Substrate: The reactant that undergoes a chemical change during enzymatic reaction.

Enzyme-Substrate Complex and Induced Fit

Complex forms when substrates bind; induced fit model describes how binding alters shape to enhance catalysis.

Cofactors and Prosthetic Groups

Cofactors: Non-protein components required for enzyme activity (may be inorganic).
Prosthetic groups: Non-amino acid compounds permanently attached to enzymes.

Enzyme Regulation

Competitive inhibitors: Compete with substrates for active site binding.
Noncompetitive inhibitors: Bind elsewhere, altering enzyme shape and function.
Allosteric regulation: Modulation of enzyme activity through non-active site binding.

Feedback Inhibition

Pathway regulation where the end product inhibits the first enzyme to prevent overproduction.

Cell Theory

All living organisms are made of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.

Plasma Membrane

Acts as an outer barrier, selectively permeable; regulates entry/exit of substances.

Prokaryotic vs. Eukaryotic Cells

Both contain DNA, ribosomes, cytosol, and a plasma membrane.
Prokaryotic: No membrane-bound organelles, with a single circular chromosome.
Eukaryotic: Membrane-bound organelles, multiple chromosomes within a nuclear envelope.

Eukaryotic Cell Parts

Major components include the nucleus, cytoplasm, and plasma membrane.

Nucleus and Chromosomes

Nucleus: Site of DNA replication and transcription, containing a nucleolus for rRNA synthesis.
Chromosomes: Structures made from condensed chromatin, housing genetic information.

Ribosomes

Composed of rRNA and proteins; essential for protein synthesis, either free in cytoplasm or attached to the rough ER.

Endomembrane System

Composed of various organelles (e.g., ER, Golgi apparatus, lysosomes) involved in the synthesis, modification, and transport of proteins.

Endoplasmic Reticulum

Rough ER: Studded with ribosomes for protein production and modification.
Smooth ER: Synthesizes lipids and detoxifies harmful substances.

Golgi Apparatus

Modifies ER products and dispatches them to destinations within or outside the cell.

Lysosomes

Contain hydrolytic enzymes for breaking down macromolecules; involved in intracellular digestion.

Mitochondria and Chloroplasts

Mitochondria: Site of ATP production through cellular respiration, double-membraned structure.
Chloroplasts: Convert light energy into chemical energy through photosynthesis, also double-membraned.

Cytoskeleton

Network of protein filaments providing structural support and facilitating organelle movement.

Cell Junctions

Specialized structures that connect and bind adjacent cells; types include tight junctions, desmosomes, and plasmodesmata in plants for cytoplasmic flow.

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Description

Test your knowledge on the biochemistry of lipids, including unsaturated fatty acids, phospholipids, and the functions of fats. Additionally, explore anabolic and catabolic reactions essential for biochemical processes. This quiz will help solidify your understanding of molecular structures and energy dynamics.