Biochemistry 1 - Cell Membranes Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which DNA polymerase in eukaryotes is involved in the replication of mitochondrial DNA?

DNA polymerase β

DNA polymerase δ

DNA polymerase γ (correct)

DNA polymerase α

What is the primary role of the promoter in the transcription process?

To replicate the DNA strand

To stabilize the RNA strand

To synthesize RNA from DNA

To regulate the initiation of transcription (correct)

Which enzyme is responsible for the replacement of RNA primers with DNA during DNA replication?

DNA ligase

DNA polymerase I (correct)

Primase

DNA polymerase III

In prokaryotic DNA replication, which strand is synthesized continuously?

Leading strand Signup and view all the answers

What type of mutation is characterized by a change in a single nucleotide?

Point mutation Signup and view all the answers

Which DNA polymerase in eukaryotes is responsible for replacing missing DNA parts?

DNA polymerase β Signup and view all the answers

Mismatch repair in prokaryotes primarily involves which DNA polymerases?

DNA polymerase I and II Signup and view all the answers

What is the main structural difference in the initiation of replication between prokaryotes and eukaryotes?

Eukaryotes have multiple origins of replication Signup and view all the answers

What effect does negative supercoiling have on transcription activity?

It enhances transcription activity. Signup and view all the answers

Which of the following represents the correct order of DNA packaging from least to most condensed in eukaryotic cells?

Nucleosome -> Chromatin -> Chromosome Signup and view all the answers

Which type of RNA is responsible for transporting amino acids during protein synthesis?

tRNA Signup and view all the answers

What is the primary role of topoisomerase II in DNA replication?

To introduce negative supercoils. Signup and view all the answers

What role does the protein kinase play during the initiation of transcription in eukaryotes?

It activates RNA polymerase II. Signup and view all the answers

How does Chargaff's rule relate to the structure of DNA?

It states the number of purines equals the number of pyrimidines. Signup and view all the answers

Which of the following statements about RNA polymerases in eukaryotes is incorrect?

RNA polymerase III cannot be inhibited by α-amanitin. Signup and view all the answers

During DNA replication, what ensures that the daughter strands are complementary to the parent strands?

Base pairing rules. Signup and view all the answers

Which of the following modifications is NOT involved in the maturation of eukaryotic mRNA?

Methylation of codons Signup and view all the answers

What is a unique feature of mRNA compared to other types of RNA?

It carries the code from DNA to the ribosome. Signup and view all the answers

Which form of DNA replication leads to the production of four non-identical daughter cells?

Meiosis. Signup and view all the answers

Which types of regulatory elements are considered cis-regulatory factors?

Promoters and enhancers Signup and view all the answers

Which of the following statements describes the role of snRNA in eukaryotic transcription?

It assists in the removal of introns during splicing. Signup and view all the answers

What is the universal start codon for the translation process?

AUG Signup and view all the answers

Which of the following modifications in chromatin is directly associated with gene silencing?

DNA methylation Signup and view all the answers

How does the process of elongation in transcription begin?

The helicase uncoils the DNA. Signup and view all the answers

Study Notes

BIOCHEMISTRY 1 - Midterm 1 Content

Cell Membranes:
- Cells without a nucleus are prokaryotes (bacteria, pathogens)
- Cells with a nucleus are eukaryotes (animals, plants, fungi)
- Plasma membrane separates the cell from its environment.
- Internal membranes separate subcellular organelles within the cytoplasm.
- Components: lipids (bilayer of cholesterol and simple/complex lipids), proteins, and carbohydrates.
- Lipids (phospholipids): major components of the cell membrane, amphipathic (hydrophilic head, hydrophobic tails), glycerophospholipids form the backbone, sphingolipids include ceramides, sphingomyelins, cerebroside, and gangliosides.
- Movement of lipids in the membrane (rotation, lateral diffusion, transversal diffusion via flippase, floppase, or scamblase).
- Cholesterol provides rigidity and contributes to atherosclerosis.
- Proteins (60% of the membrane): integral (embedded, hydrophobic/hydrophilic), peripheral (loosely bound).
- Carbohydrates: branched oligosaccharides attached to lipids (glycolipids) or proteins (glycoproteins).
- Membrane fluidity increases with temperature and unsaturated fatty acids.
- Properties of membranes: selective barriers, metabolic compartments, dynamic and continuously renewed.
- Cell membranes are asymmetric.
Transport Across the Membrane:
- Passive transport: follows the concentration gradient; no ATP needed.
  - Simple diffusion: through the membrane (uncharged/lipid-soluble).
  - Facilitated diffusion: with carrier molecules or pores (proteins, glucose transporters, carnitine, aquaporins).
- Active transport: against the concentration gradient; requires ATP.
  - Primary active transport: carrier proteins (sodium-potassium pump).
  - Secondary active transport: coupled with the movement of another molecule (osmotic gradient).
- ABC transporters
- Proton pumps (in the respiratory chain)
- SGLT-1 - SGLT2 (in epithelial and kidney cells)
Amino Acids and Proteins:
- Properties of amino acids (AA): chiral carbon, L-form common in proteins.
- Protein structure: primary (sequence of AAs), secondary (alpha-helix/beta-sheet), tertiary (3D structure, interactions of side chains), and quaternary (multiple polypeptide chains).
- Types of proteins (globular: spherical, water soluble, enzymes; fibrous: sheet-like, water insoluble, collagen, keratin, elastin).
- Protein structure determination by techniques like electrophoresis, spectroscopy, x-ray crystallography.
- Structure, function, and properties
Enzymes: Proteins with Catalytic Power:
- History of enzyme discovery; Enzymes are made to accelerate reactions.
- Role of enzymes in intermediary metabolism and biological processes; Highly specialized (1000-4000 enzymes per cell).
- Properties of enzymes; Active and catalytic sites.
  - Mechanisms by which enzyme function; Induced-fit model
  - Factors affecting enzyme activity (temperature, pH, concentration, inhibitors); Michaelis-Menten kinetics
  - Types of enzymes (serine proteases: chymotrypsin, trypsin, elastase).
DNA and RNA Molecules:
- Difference between DNA and RNA (deoxyribose vs. ribose, presence of T vs. U)
- Nucleotides & nucleosides
- Structure of DNA; Double helix, base pairing (A-T, G-C)
- Types of DNA: A-DNA, B-DNA, Z-DNA.
- Difference between prokaryotic and eukaryotic DNA structure.
- Levels of DNA structure: DNA→ Nucleosome→ Chromatin→ Chromosome
- DNA replication; semi-conservative
- Enzymes involved in DNA replication (DNA polymerase, primase, ligase)
Transcription:
- DNA to RNA; RNA synthesis
- Steps in transcription: initiation, elongation, termination
  - Promoters, RNA polymerase, coding region.
- Transcription factors and types of RNA polymerases (prokaryotes vs. eukaryotes)
  - Prokaryotes-Polycistronic; Eukaryotes-monocistronic, Introns vs. Exons
- Maturation of RNA (capping, tailing, splicing.)
Translation:
- Process of protein synthesis (mRNA, tRNA, ribosomes); Universal start codon(AUG, for Met)
- Structure of mRNA, tRNA, Ribosomes
- Types of Ribosomes: Prokaryotic vs Eukaryotic
- Steps in translation: initiation, elongation, and termination
Regulation of gene expression.
Post-transcriptional & post-translational modification
Structure Proteins:
- Keratin; alpha-helix structure, S-S bonds, H-bonds, and ionic interactions, found in wool, feathers, hair
- Collagen; Triple helix structure, Gly, Pro, hydroxyproline, hydroxylysine, found in skin, bones, tendons
- Elastin; cross-linked protein, found in lungs, aorta, flexible connective tissue.
Fibronectin, laminin, proteoglycans: extracellular matrix proteins: cell adhesion, regulate molecule movement.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the essential components and functions of cell membranes in eukaryotic and prokaryotic cells. This quiz covers lipid structures, membrane proteins, and the role of cholesterol in membrane dynamics. Prepare for your Midterm 1 in Biochemistry!