Cell Biology and Genetic Expression Quiz

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Questions and Answers

What process is necessary for the transport of protein and RNA through nuclear pores?

Selective, energy-requiring transport (correct)

Simple diffusion

Passive transport

Osmosis

What type of RNA is produced from the genes in the nucleus and is primarily involved in protein synthesis?

Ribosomal RNA (rRNA)

Small nuclear RNA (snRNA)

Transfer RNA (tRNA)

Messenger RNA (mRNA) (correct)

What effect does phosphorylation have on the protein involved in Na+ transport?

Phosphorylation causes the protein to change shape. (correct)

Phosphorylation increases Na+ concentration inside the cell.

Phosphorylation enhances K+ binding affinity.

Phosphorylation prevents Na+ from binding.

What is the primary function of mRNA in the context of genetic expression?

To carry the code for protein synthesis Signup and view all the answers

What are nucleoli primarily involved in synthesizing?

Ribosomal RNA (rRNA) Signup and view all the answers

In the Na+-Glucose symporter, what direction does Na+ flow?

Down its concentration gradient. Signup and view all the answers

Which type of endocytosis involves the engulfing of large particles?

Phagocytosis Signup and view all the answers

How does the number of proteins produced in a cell compare to the number of genes?

More proteins are produced than there are genes. Signup and view all the answers

What role do lysosomes play in the cell after phagocytosis?

They isolate and digest engulfed proteins and lipids. Signup and view all the answers

What term refers to all of the proteins produced by the genome in an organism?

Proteome Signup and view all the answers

What stage of genetic expression follows the synthesis of RNA?

Genetic translation Signup and view all the answers

Which process is characterized by the selective uptake of specific ligands through receptor binding?

Receptor-mediated endocytosis Signup and view all the answers

What is the initial state of a primary lysosome?

It contains digestive enzymes in an acidic environment. Signup and view all the answers

Which statement about gene expression is true?

Some cells can express different genes than others. Signup and view all the answers

What happens to K+ after it binds to the Na+ transport protein?

It causes Na+ to be released outside the cell. Signup and view all the answers

Which type of endocytosis is known for sampling the extracellular environment through fluid intake?

Pinocytosis Signup and view all the answers

What are the two polypeptide chains of insulin linked by?

Disulfide bonds Signup and view all the answers

What type of cell division results in gametes containing half the number of chromosomes?

Meiosis Signup and view all the answers

During DNA replication, what is the role of DNA helicases?

To break the hydrogen bonds between DNA bases Signup and view all the answers

How many amino acids are in the longer chain of insulin produced from proinsulin?

30 amino acids Signup and view all the answers

What is produced at the end of DNA replication?

Two new double-helix DNA molecules Signup and view all the answers

What type of bond forms between adenine and thymine during DNA replication?

Hydrogen bond Signup and view all the answers

Which enzyme is responsible for joining nucleotides together to form new DNA strands?

DNA polymerase Signup and view all the answers

What is the primary function of proinsulin before its conversion to insulin?

It serves as a precursor for insulin Signup and view all the answers

What role do cyclin D proteins play in the cell cycle?

They activate cyclin-dependent kinases. Signup and view all the answers

What is the primary mechanism by which gene silencing occurs in epigenetic inheritance?

Methylation of cytosine bases Signup and view all the answers

What is the primary function of the p53 protein?

To stall cell division when DNA is damaged. Signup and view all the answers

How does the process of acetylation affect gene expression?

It leads to a more relaxed chromatin structure. Signup and view all the answers

What characterizes the relationship between oncogenes and proto-oncogenes?

Oncogenes are altered forms of proto-oncogenes. Signup and view all the answers

What role does crossing-over play in genetic variation?

It allows for the recombination of genetic material between homologous chromosomes. Signup and view all the answers

Which of the following best describes apoptosis?

Cell shrinkage with intact membranes. Signup and view all the answers

Which of the following diseases is associated with problems in epigenetic inheritance?

Cancer Signup and view all the answers

Which factors can lead to the conversion of proto-oncogenes to active oncogenes?

Genetic mutations and chromosome rearrangements. Signup and view all the answers

What type of cell death is characterized by the swelling and rupture of cells?

Necrosis. Signup and view all the answers

What is a consequence of reduced DNA methylation in cancers?

Activation of normally silenced genes. Signup and view all the answers

What is the impact of epigenetic changes on identical twins?

They may show differences in gene expression despite having the same genetic makeup. Signup and view all the answers

What triggers the intrinsic pathway of apoptosis?

DNA damage or oxidative stress. Signup and view all the answers

What is a crucial function of tumor suppressor genes?

To inhibit the development of cancer. Signup and view all the answers

What is the role of histone modifications in gene expression?

They influence how tightly or loosely the chromatin is compacted. Signup and view all the answers

Which of the following describes gene silencing that is inherited across generations?

Epigenetic inheritance Signup and view all the answers

What is a codon?

A code word for a specific amino acid Signup and view all the answers

What happens to proteins after they are synthesized on ribosomes attached to the rough endoplasmic reticulum?

They are modified within the cisternae. Signup and view all the answers

What role does the leader sequence play in protein synthesis for secretion?

It serves as an address to direct the protein into the ER. Signup and view all the answers

Which statement about preproinsulin is true?

It enters the cisterna as a polypeptide composed of 109 amino acids. Signup and view all the answers

How does the rough endoplasmic reticulum aid in the transport of proteins destined for secretion?

It provides a cavity for protein modification and packaging. Signup and view all the answers

What modification happens to insulin once it is in the rough ER?

Carbohydrates are added to the protein structure. Signup and view all the answers

During translation, how is the sequence of specific amino acids determined?

By the sequence of codons in the mRNA. Signup and view all the answers

Which of the following best describes the function of polyribosomes?

They synthesize proteins that remain within the cell. Signup and view all the answers

Study Notes

The Cell

The cell is the fundamental unit of structure and function in the body
Cell functions are carried out by subcellular components called organelles
Plasma membrane regulates communication between inside and outside the cell, and facilitates movement
Cells appear simple under a light microscope, but their complex physiology is evident at subcellular level

Plasma Membrane and Associated Structures

Composed of a phospholipid bilayer with embedded proteins
Hydrophobic tails face inwards, hydrophilic heads face outwards
Selectively permeable, controlling substances moving in and out
Proteins facilitate specific transport and function as receptors, enzymes
Contains carbohydrates (glycoproteins/glycolipids) as markers
Cholesterol regulates flexibility
Bulk transport processes (phagocytosis, endocytosis, exocytosis) enable movement of materials across the membrane

Cell Components and Functions

Plasma membrane: Forms the outer boundary of the cell, controls material passage
Cytoplasm: Contains organelles in a jelly-like substance (cytosol)
Endoplasmic reticulum(ER): Rough ER (with ribosomes) processes proteins, smooth ER modifies them.
Ribosomes: Synthesize proteins
Golgi complex: Processes and packages proteins and other materials
Mitochondria: Generate energy (ATP) through cellular respiration
Lysosomes: Contain enzymes to digest cellular materials
Peroxisomes: Detoxify harmful substances
Centrosome: Helps organize cell division
Vacuoles: Store substances
Microfilaments and microtubules: Provide structural support and movement
Cilia and flagella: Involved in cell movement
Nuclear envelope: Encloses the nucleus, has pores for material passage
Nucleolus: Involved in ribosome production
Chromatin: Contains DNA, packages genetic material

Cytoplasm and Cytoskeleton

Cytoplasm is the material within a cell encompassing the cytosol and organelles.
The cytoskeleton includes microtubules and microfilaments providing structural support and movement.
Organelles like the nucleus, vesicles, and proteins use the cytoskeleton as a transport system within the cell.

Cell Membrane and Transport

The membrane is selectively permeable allowing some materials to pass but not others.
Passive transport happens without energy expenditure. It includes diffusion (simple/facilitated).
Osmosis is the movement of water across a membrane from a low concentration of solute to a high one.
Active transport employs energy(ATP) to move materials against their concentration gradient.
Active transport via vesicles enables the transport of large particles like in phagocytosis, pinocytosis, and receptor-mediated endocytosis

Cell Nucleus

Most cells have a single nucleus. Exceptions include skeletal muscle and mature red blood cells.
The nucleus is surrounded by a double membrane (nuclear envelope)
Nuclear pores regulate the passage of molecules in and out of the nucleus
Chromatin contains DNA which functions as a template for RNA and proteins

Genome and Proteome

Genome refers to all genes in a cell
Human genome contains around 25,000 genes
Proteome refers to all the proteins that a genome produces
The number of proteins exceeds genes because one gene can code for multiple proteins in a single cell.

RNA Synthesis

Genes are DNA segments containing instructions for making specific proteins
RNA synthesis copies genetic code from DNA to make mRNA
RNA molecules (mRNA, tRNA, and rRNA) are essential in protein synthesis

Protein Synthesis and Secretion

mRNA plays a crucial role in translating the genetic code into amino acid sequences for protein synthesis
mRNA binds to ribosomes.
Ribosomes translate mRNA's codons into amino acid sequences.
Newly formed proteins undergo modifications and are sometimes dispatched from the cell

DNA Synthesis and Cell Division

When a single cell replicates, each old strand serves as a template for a new strand
Growth, repair, and reproduction are processes involving cell cycle stages and cell division.

Mitosis

Mitosis involves cell division resulting in two daughter cells with the same number of chromosomes as the original cell
Mitosis is the process of dividing a cell's nucleus, before cytoplasmic division
The stages of mitosis are prophase, metaphase, anaphase, and telophase

Meiosis

Meiosis is responsible for producing gametes (sperm/ova) with half the number of chromosomes, compared to a parent cell.
Meiotic cell division results in four daughter cells.
Crossing-over during meiosis promotes genetic diversity.

Hypertrophy and Hyperplasia

Cells can increase in size (hypertrophy) or number (hyperplasia)
Muscle growth from exercise is an example of hypertrophy.
Callus formation demonstrates hyperplasia

Cell Death

Cell death occurs naturally (apoptosis) or pathologically (necrosis)
Apoptosis is a programmed cell suicide process helping the body rid itself of unneeded or damaged cells Apoptosis can be triggered by intrinsic(internal signals) or extrinsic (external factors) mechanisms

Mitochondria

Found in the cells, except mature red blood cells, the main function is to produce energy (ATP)
Mitochondria contains their own DNA which allows them to reproduce independently.
Mitochondria are enveloped by two membranes, an inner and outer membranes.

Ribosomes

Responsible for the production of proteins
Found either free in the cytoplasm or attached to the endoplasmic reticulum.
Ribosomes are composed of rRNA

Endoplasmic Reticulum (ER)

A network of membranes extending throughout the cytoplasm
There is rough (with ribosomes) and smooth ER

Golgi Complex

A stack of flattened, membrane-bound sacs (cisternae) for the processing and packaging of proteins.
Proteins move through the Golgi complex

Lysosomes

Membrane-bound sacs containing digestive enzymes for the breakdown and recycling of cellular components.
The role of lysosomes is recycling cell components

Clinical Applications

Cell cycle abnormalities can play a role in tumors
Stem cells can differentiate into various cell types, essential for tissue repair and development
A malfunctioning cell cycle can lead to diseases like cancer.
Apoptosis is a normal process eliminating damaged cells
Understanding cell division/cell death can lead to new treatments for diseases

Epigenetic Inheritance

Epigenetic inheritance is the passing of traits without changing the DNA sequence
Changes to histone proteins and DNA methylation are examples of epigenetic mechanisms
Genes can be silenced or reactivated without alterations to the DNA base sequence.

Protein Function

Proteins play various roles in the cell including transport, catalysis, and structural support.
Protein synthesis uses a genetic code translated by mRNA.

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Description

Test your knowledge on essential processes in cell biology, focusing on protein synthesis, RNA transport, and gene expression. Questions cover topics such as nuclear pore transport, mRNA functions, and endocytosis mechanisms. Perfect for students looking to solidify their understanding of cellular functions.