Biomolecules: Nucleic Acids and Carbohydrates

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Questions and Answers

Which component is NOT part of nucleic acids?

Organic base

Phosphate group

Amino group (correct)

5-carbon sugar

What is a primary function of nucleic acids?

Store genetic information (correct)

Aid in digestion

Form structural components of membranes

Provide energy

Which statement accurately describes a characteristic of omega-3 fatty acids?

They are non-essential fats.

They primarily provide the body with energy.

They are abundant in the diet.

They are essential for heart, brain, and metabolism. (correct)

Which carbohydrate is classified as a disaccharide?

Sucrose Signup and view all the answers

During which phase of the cell cycle does DNA replication occur?

S phase Signup and view all the answers

What describes the tertiary structure of a protein?

The overall 3D shape formed by the interactions between secondary structures Signup and view all the answers

What type of sugar is ribose?

Monosaccharide Signup and view all the answers

Which of the following is a purine base?

Adenine Signup and view all the answers

What is a key characteristic that differentiates prokaryotes from eukaryotes?

Number of membrane-bound organelles Signup and view all the answers

Which component is primarily found in the bacterial cell wall?

Peptidoglycan Signup and view all the answers

What is the function of the Golgi bodies in a cell?

Sorting and modifying proteins Signup and view all the answers

What roles do secretory vesicles perform in the cell?

Deliver contents to the extracellular space Signup and view all the answers

What is a function of the plasma membrane?

Maintaining osmotic pressure Signup and view all the answers

Which of the following describes the endoplasmic reticulum's functions?

Protein and lipid synthesis Signup and view all the answers

What unique feature characterizes prokaryotic DNA?

Circular molecules Signup and view all the answers

What is the major site of cellular metabolism within the cell?

Cytosol Signup and view all the answers

What initiates the entry into the cell cycle at the restriction point?

Mitogenic stimuli from proteins Signup and view all the answers

During which phase does Cyclin D interact with Cyclin-dependent kinases (Cdks) 4 and 6?

G1 phase Signup and view all the answers

What is the purpose of checkpoint mechanisms in the cell cycle?

To ensure proper cell division and DNA integrity Signup and view all the answers

Which cyclins accumulate and initiate DNA synthesis during the S phase?

Cyclin A and E Signup and view all the answers

What is the result of the primary spermatocyte undergoing meiosis?

Two secondary spermatoctytes are produced Signup and view all the answers

What happens to the secondary oocyte after it is formed during oogenesis?

It undergoes meiosis to form a mature ovum Signup and view all the answers

Which checkpoint is specifically associated with the G1 phase of the cell cycle?

Cell size checkpoint Signup and view all the answers

Which cyclins are involved in triggering mitosis during the M phase?

Cyclin A and B Signup and view all the answers

What is the primary function of the spliceosome during mRNA processing?

To catalyze the removal of introns from pre-mRNA Signup and view all the answers

Which modification is essential for protecting immature mRNA from degradation?

Addition of a 5' methylated guanine cap Signup and view all the answers

What forms the transcription initiation complex?

TF and RNA polymerase Signup and view all the answers

Why is polyadenylation important for mRNA?

It stabilizes the RNA molecule Signup and view all the answers

Where is the promoter region usually located in relation to the transcription start site?

At the 5' end or directly upstream of the transcription initiation site Signup and view all the answers

What defines the open reading frame (ORF) within mature mRNA?

The sequence of codons to be translated into protein Signup and view all the answers

What is the primary role of RNA polymerase during transcription?

To synthesize mRNA by matching complementary bases to DNA Signup and view all the answers

What role does tRNA play in the translation process?

It reads the codons in mRNA and carries the corresponding amino acids Signup and view all the answers

What are the three sites on the ribosome where tRNA can attach called?

P, A, and E sites Signup and view all the answers

What is the TATA box's significance in eukaryotic transcription?

It indicates where transcription begins Signup and view all the answers

Which enzyme is primarily responsible for initiating transcription?

RNA polymerase Signup and view all the answers

What happens to the intron after it is spliced out from pre-mRNA?

It detaches and can be reused for splicing Signup and view all the answers

What is the primary purpose of the untranslated regions (UTRs) in mature mRNA?

To regulate the translation process Signup and view all the answers

What is the function of the core promoter in eukaryotic genes?

To control the synthesis of RNA transcripts Signup and view all the answers

What occurs during the pre-initiation step of transcription?

The DNA double helix is unwound Signup and view all the answers

What structure results from the unwinding of DNA during replication?

Replication fork Signup and view all the answers

Study Notes

Prokaryotes vs. Eukaryotes

Prokaryotes are defined as "before the kernel" and do not have membrane-bound organelles.
They contain three times less genetic material than the smallest eukaryotic cells and possess DNA in singular circular molecules.
Eukaryotes, meaning "true kernel," have membrane-bound organelles and larger genomes, with DNA stored in chromosomes.
Both cell types are surrounded by a plasma membrane and share similar macromolecular components.

Parts of the Cell

Cell Wall: Composed of cellulose, microfibrils, hemicellulose, pectin, lignin, and soluble proteins. Bacterial cell walls primarily contain peptidoglycan (NAG and NAM).
Plasma Membrane: A semi-permeable barrier regulating nutrient intake, waste filtration, and cell communication.
Nucleus: Contains chromosomes within a double membrane structure; the outer membrane connects to the rough endoplasmic reticulum (RER).
Cytosol: Hosts the cytoskeleton for cell shape and motility; key site for cellular metabolism due to abundant enzymes.
Endoplasmic Reticulum (ER): Largest membrane system in eukaryotic cells; rough ER synthesizes proteins, while smooth ER synthesizes lipids.
Golgi Bodies: Act as traffic controllers for sorting proteins, modifying secretory proteins within the Golgi lumen.
Secretory Vesicles: Transport modified proteins and release contents through exocytosis; can fuse for storage.
Small Vesicles: Coated with clathrin, guiding fusion with target membranes to deliver contents.
Nucleic Acids: Store genetic information and regulate gene expression through protein synthesis instructions.
Lipids: Integral structural components of biomembranes.
Carbohydrates: Primary energy source (glucose) and significant in nucleic acid composition (ribose and deoxyribose). Types include monosaccharides, disaccharides, oligosaccharides, and polysaccharides.

Omega Fatty Acids

Omega-3: Essential for heart, brain, and metabolism; often under-consumed.
Omega-6: Energy-providing, abundant in the diet.
Omega-9: Non-essential fats produced by the body.

Amino Acids Structure

Primary Structure: Sequence of amino acids in a polypeptide chain.
Secondary Structure: Folding into patterns like alpha-helices.
Tertiary Structure: Further folding and organization of secondary structures.
Quaternary Structure: Assembly of multiple polypeptide chains into a functional protein.

Nucleic Acids Characteristics

Comprised of phosphate groups, five-carbon sugars (pentose), and organic bases.
Purines include adenine and guanine; pyrimidines consist of cytosine, thymine, and uracil.
Leading strand synthesizes from 5' to 3'; lagging strand runs from 3' to 5'.

The Cell Cycle

The cell cycle consists of G1 (transcription and translation), S (DNA replication), and G2 (preparation for mitosis).
Mitosis occurs in somatic cells; meiosis occurs in sex cells and involves stages like prophase, metaphase, anaphase, and telophase.

Meiosis and Mitosis Processes

Prophase 1 features synapsis and crossing over.
Chromosomes condense, the nuclear envelope fragments, and spindle fibers attach during prophase's later stages.
Telophase 1 involves partial assembly of the nuclear envelope and cytokinesis.

Cyclins and Cell Cycle Regulation

Cyclin D responds to mitogenic stimuli, binds to cyclin-dependent kinases (Cdks) (4 and 6) in G1 phase, triggering transcription that synthesizes Cyclins A and E for S phase.
Following S phase, mitotic cyclins (A and B) interact with CDK1 to initiate M phase, regulated by checkpoints on cell size, nutrient availability, and DNA damage.

RNA Transcription and Processing

RNA polymerase catalyzes transcription by binding to the promoter region, indicating where transcription begins (often contains a TATA box).
Pre-mRNA undergoes splicing, removing introns with the aid of spliceosomes forming mature mRNA.
Processing involves 5' capping and 3' polyadenylation to stabilize and protect the mRNA.

Translation Process

mRNA is translated into proteins within the ribosome; each tRNA carries specific amino acids and matches codons in mRNA.
The initiation site for translation involves the attachment of the mRNA and the first tRNA, with ribosomes facilitating the formation of polypeptide chains.

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Description

This quiz explores essential biomolecules, focusing on nucleic acids and carbohydrates. Learn about their roles in genetic information storage, energy sources, and cell membrane composition. Test your understanding of these vital components of life.