Cell Biology Lecture Review (test)

Flashcards covering key concepts, structures, and functions of mammalian cells and their organelles based on the provided lecture notes.

What is the smallest functional unit of an organism?

Cells

How do cellular activities relate to organismal functions?

Cellular activity leads to organismal functions.

What is the typical size range of a cell?

10-140 nM

What is the usual diameter range for most cells?

10-15 μm

Which cell is an exception to the typical cell diameter, and what is its size?

An oocyte, 140 μm

What limits cell size?

Surface area to volume relationship

What happens to the surface area to volume relationship as cell radius increases?

Volume increases more than surface area.

What defines a eukaryotic cell?

It has a nucleus.

What is the main function of the cell membrane?

It forms a selectively permeable barrier.

Name some membrane-bound organelles found in a eukaryotic cell.

Nucleus, Mitochondria, Golgi apparatus, Endoplasmic reticulum, Lysosomes, Peroxisomes.

Name some non-membrane-bound organelles found in a eukaryotic cell.

Ribosomes, Proteasomes, Cytoskeleton, Centrosome and centrioles, Cilia.

What is the primary component of the membrane bilayer?

Phospholipids.

In phospholipids, where are the heads and tails located in the bilayer?

Heads are on the outside, tails are inside.

What term describes a molecule that has both hydrophilic and hydrophobic properties?

Amphipathic

What is the main function of the plasma membrane?

To separate two aqueous compartments and form a selectively-permeable barrier.

What is the glycocalyx composed of, and where is it located?

Glycolipids, glycoproteins, and carbohydrates, forming a coat on the extracellular surface of the membrane.

What two components determine the fluidity of the cell membrane bilayer?

Phospholipids and cholesterol.

What role do phospholipids play in the fluidity of the bilayer?

They contribute to fluidity.

What role does cholesterol play in the fluidity of the bilayer?

It contributes to rigidity.

Where are peripheral proteins located in the plasma membrane?

At the extracellular or intracellular face, bound to the surface itself or covalently bonded to integral proteins.

How are integral proteins associated with the plasma membrane?

They are embedded in the plasma membrane or attached via covalent bonds.

What type of integral protein spans the entire cell membrane?

Transmembrane proteins.

List some functions of plasma membrane proteins.

Carriers, Channels, Receptors, Recognition, Enzymes, Cell-cell interactions.

Name the three main components of the cytoskeleton.

Microtubules, Intermediate filaments, Microfilaments.

What protein are microtubules made of?

Tubulin.

Describe the structure of microtubules.

Long hollow cylinders.

Name a function of microtubules related to cell division or motility structures.

They are components of spindle fibers, cilia, and flagella.

What is the role of microtubules in cellular transport?

They provide a track for the movement of cargo throughout the cytosol, aided by molecular motors like dynein and kinesin.

In what specific cell structure are microtubules important for fast transport of substances?

Nerve cell axons.

What protein are microfilaments made of?

Actin (thin filament).

Where are microfilaments typically located within the cell?

In the periphery of the cell.

What is a key function of microfilaments during cell division?

They are important in cytokinesis.

What molecular motor is associated with actin in microfilaments, and what function does this complex serve in muscle cells?

Myosin (thick filament), forming a contractile apparatus responsible for muscle contraction.

What are intermediate filaments composed of?

Polymers of protein subunits.

Name two specific proteins that make up intermediate filaments and give an example of where each is found.

Keratin (epithelial cells) and Desmin (muscle).

What is the primary function of intermediate filaments?

To provide mechanical stability to cells.

What is the monomer, location, and specialized function of Microtubules?

Monomer: tubulin, Location: Nucleus to plasma membrane, Specialized Function: Transport of substances in nerve axons.

What is the monomer, location, and specialized function of Microfilaments?

Monomer: actin, Location: Near plasma membrane, Specialized Function: Muscle contraction.

What is the function of flagella and in which human cell type are they primarily found?

They propel cells, primarily found in sperm.

What is the function of cilia?

Mixing of substance at the cell surface.

What is the structural arrangement of microtubules in both cilia and flagella?

9 + 2 circles.

What is the basal body?

The point or origin of growth for cilia and flagella.

What is a centriole composed of?

A cylinder composed of 9 groups of microtubule triplets.

What is the centrosome, and what is its role in cell division?

It is the microtubule organizing center, containing two centrioles at right angles, and microtubules extending from it form spindle fibers important for mitosis.

What are the primary functions of the nucleus?

Site of DNA storage, DNA replication, and transcription.

What is the nucleolus, and what is its function?

A small, round, dense structure within the nucleus, which is the site of transcription of ribosomal DNA.

Describe the nuclear envelope.

It is a double membrane; the outer membrane is studded with ribosomes, and the inner membrane is smooth.

What is the function of nuclear pores?

They are transport pathways for molecules, acting as a selective passageway for molecules with a specific signal (nuclear localization sequence).

What is the primary function of ribosomes?

Site of protein synthesis.

What are ribosomes made of?

Ribosomal RNA and protein.

What are the two main locations where ribosomes can be found in the cell?

On the cytosolic membrane of the Rough ER and free floating in the cytosol.

What are the main functions of the endoplasmic reticulum?

Site for protein synthesis, lipid synthesis, and Ca2+ storage.

What structural features are common to all types of endoplasmic reticulum?

They are membrane-bound, continuous with the nuclear envelope, composed of sacs called cisternae, and form a continuous network of cisternae and tubules.

What distinguishes rough endoplasmic reticulum (RER) from smooth endoplasmic reticulum (SER)?

RER has ribosomes, while SER lacks ribosomes.

What is the primary function of the rough endoplasmic reticulum (RER)?

Protein modification within its lumen.

What are the primary functions of the smooth endoplasmic reticulum (SER)?

Lipid and carbohydrate synthesis.

What is sarcoplasmic reticulum, and what is its specific function?

It is a type of smooth ER found within muscle cells, and its function is calcium storage.

What are the primary functions of the Golgi apparatus?

Protein/lipid modification, sorting, and packaging.

What does the Golgi apparatus receive, and from where?

Proteins and lipids from the ER.

How does the Golgi apparatus chemically modify proteins and lipids?

By adding sugars (forming glycoproteins and glycolipids).

How does the Golgi apparatus release modified proteins and lipids?

It packages them into secretory vesicles for exocytosis, delivering them to the plasma membrane or other cellular sites.

Where does protein synthesis occur?

In free-floating ribosomes in the cytoplasm or on fixed ribosomes on the Rough Endoplasmic Reticulum (RER).

After synthesis, where do proteins destined for modification by the Golgi apparatus travel?

They are released into the cytosol in transport vesicles and travel to the Golgi Apparatus.

What happens to proteins after modification in the Golgi Apparatus?

They are packaged into secretory vesicles and delivered to the plasma membrane or other locations within the cell.

What is the primary function of mitochondria?

Site of oxygen-dependent ATP production (powerhouse of the cell).

How many membranes do mitochondria have, and what is a key feature of the inner membrane?

Two membranes; the inner membrane has electron transport chain proteins.

What are cristae?

Shelf-like projections of the inner mitochondrial membrane.

Where in the mitochondrion would you find the intermembrane space and the inner mitochondrial matrix?

The intermembrane space is between the inner and outer membranes; the inner mitochondrial matrix is within the inner membrane.

Do mitochondria contain their own genetic material? If so, describe it.

Yes, they have their own circular DNA with about 37 genes.

How is mitochondrial DNA typically inherited?

Maternally.

What is the main function of lysosomes?

They act as the 'garbage disposal' of the cell, breaking down macromolecules and worn-out organelles.

Are lysosomes single or double membrane-bound organelles?

Single membrane-bound.

What is autolysis, and what organelle is involved?

The process where lysosomes release enzymes into the cytosol to assist in the breakdown of cellular components.

What is the difference between primary and secondary lysosomes?

Primary lysosomes are before fusing to material to be degraded, while secondary lysosomes have engulfed material for degradation.

What type of reaction do peroxisomes catalyze, and what do they produce?

They catalyze reactions that produce H2O2 (hydrogen peroxide).

Are peroxisomes single or double membrane-bound organelles?

Single membrane-bound.

In which organs are peroxisomes particularly abundant?

Kidney and liver.

What are the primary functions of peroxisomes?

Detoxification, breakdown of fatty acids into smaller units, and breakdown of lipids.