Chapter 4

What are the three tenets of the Cell Theory

All organisms are composed of one or more cells. The cell is the basic structural & functional unit of all living organisms (basic unit of life). All cells come from pre-existing cells.

Cells morphology types

Eukaryotes have membrane-bound nucleus. Prokaryotes don’t.

And then divided by phylogeny (evolution history) into domains

Bacteria, archaea, and eukarya (pink is prokaryotic. Eukarya is eukaryotic).

Match the macromolecule with its basic function

Proteins perform most of the cell’s functions; Nucleic Acids store, transmit, and process information; Carbohydrates provide chemical energy, carbon, support, and identity.

What was the first object observed underneath a microscope by Robert Hooke that led to the discovery of the cell?

Plant cell- walls (cork cells).

What is one of the major advantages of phase contrast microscopy?

Living cells can be examined w/o being killed, fixed, and stained.

What microscopy would be used to see the surface area of bacterial concrete?

SEM (Scanning electron microscope)

What color is DNA in the fluorescence microscopy pictured below?

BLUE.

Which of the following microscopy techniques is best suited for visualizing protein complexes in their cellular environments without the use of preservatives?

d) Cryo-electron microscopy.

How do cells overcome cell size limitations? (3 ways)

-fold surface into microvilli (long thin projections) to increase surface area w/o large increase in volume; -divide to become more efficient; - develop organelles that perform specific tasks.

Label which statements are true or false: a) The plasma membrane is made from a hydrophilic phospholipid bilayer. b) The lipid bilayer protects the cell. c) The bilayer combines the interior environment of a cell with the exterior environment outside of a cell. d) The lipid bilayer is semi-permeable.

a) FALSE; b) TRUE; c) FALSE; d) True.

Where is the prokaryotic chromosome located?

a) Nucleoid.

Which is true about plasmids?

a) Provide antibiotic resistance.

Which is true about ribosomes?

b) Synthesize proteins from mRNA.

Which is true about pili?

a) Located on cell surface.

What does the prokaryotic exoskeleton do?

a) Maintain cell shape.

Which is true about the photosynthetic membrane?

a) Convert sunlight to chemical energy.

What is a defining feature of eukaryotic cells?

b) The true nucleus is in the membrane.

Which research method is used to study organelles?

b) Cell fractionation.

Match Organelles with their function: Mitochondria, Lysosomes, Endoplasmic Reticulum

Mitochondria: Generates energy from food; Lysosomes: Break down and recycle organelles; Endoplasmic Reticulum: Builds membrane and transport proteins.

What is the purpose of cell fractionation?

b) Separate cells into different organelles.

Which way does NOT break up cells for fractionation?

b) Centrifugation.

What is the mixture called after fractionation process?

c) Homogenate.

What do cell membranes form after disruption in cell fractionation?

b) Vesicles.

The ___ is a network of membranous sacs and tubes; active in the membrane synthesis and other synthetic and metabolic processes; has rough and smooth regions.

The Endoplasmic reticulum (ER) is a network of membranous sacs and tubes; active in the membrane synthesis and other synthetic and metabolic processes; has rough and smooth regions.

The ___ is a series of flattened membranes; involved in the secretion of proteins from cells and in reactions that link sugars to other cellular components.

The Golgi apparatus is a series of flattened membranes; involved in the secretion of proteins from cells and in reactions that link sugars to other cellular components.

The DNA molecule in the eukaryotic nucleus is circular (T/F).

False, the DNA in eukaryotic cells is linear. DNA is circular in prokaryotic cells.

Ribosomal RNA (rRNA) is synthesized from genes in the DNA of eukaryotic cells (T/F).

True! These genes are located in the nucleolus, a region within the nucleus, where rRNA is transcribed and assembled with proteins to form ribosomes.

Ribosomes specialize in producing lipids (T/F).

False, ribosomes specialize in producing proteins.

The Endomembrane system includes the….

Nuclear envelope, Endoplasmic reticulum, Golgi complex and Plasma membrane, Lysosomes and Vesicles

Chaperone proteins are primarily responsible for:

B. Facilitating the proper folding of other proteins.

A 50 Y M patient was found to have overdosed on an unknown drug that is being processed in his liver. Which of the following aids in reducing the effects of the drug on the body?

A. Smooth ER.

T/F: Proteins made in the ER enter on the cis face of the complex.

A. True.

Interaction of which of the following causes formation of a vesicle?

A. Coat and adapter proteins.

An accumulation of food molecules can hint at a dysfunctioning of which of the following?

A. Lysosomes.

Which of the following correctly matches the structure with its correct feature?

D. The inner mitochondrial membrane contains cristae.

Which of the following is not a function of microtubules?

C. Allows for muscle contraction.

Which of the following statements about microfilaments is TRUE?

B) Microfilaments are responsible for providing structural support and facilitating cell movement.

Flagella are primarily used by cells for movement and are composed of a protein called tubulin (T/F)

True.

Which of the following statements accurately describes intermediate filaments?

C) Intermediate filaments provide structural support, can occur singly or in networks, and are tissue-specific in protein composition.

On actin filaments, the ATP-binding cleft on the monomer points toward the minus end, which is also referred to as the "pointed" end. T or F

True.

Which of the following is NOT a function of microfilaments?

D) Microfilaments are the primary components of the mitotic spindle, responsible for chromosome separation during cell division.

Which of the following statements correctly describes the structure and function of cilia and flagella?

B) Flagella and cilia both share a common structure of microtubules arranged in a ring with two single microtubules in the center, and they are anchored by a basal body.

Flagella move with a back-and-forth motion perpendicular to the axis of the cilium. Cilia move in a snake-like motion in the same axis as of the flagellum. True or False

False.

_ are responsible for storing starch, and are colorless in appearance.

D. Amyloplasts.

The ___, inner compartment of the chloroplast, contains stacked ___ ___, which are collectively called ___.

The inner compartment of the chloroplast, stroma, contains stacked thylakoid membranes, which are collectively called grana.

What structure is made up of pectin and holds adjacent cell walls together? (Hint: it is in the MIDDLE of two cell walls)

MIDDLE LAMELLA!.

Match the Cell Junctions: Tight Junctions, Gap Junctions, Anchoring Junctions

Tight Junctions: Close-knit connections between cells, usually around internal organs, includes the fusion of proteins to plasma membranes of adjacent cells. Gap Junctions: Allow small molecules to pass from between cells, hollow proteins connect the cytoplasms of both cells (ex: Heart muscle tissue). Anchoring Junctions: Creating ‘belt-like’ structures around cells to pull adjacent cells together. Most prevalent in areas prone to stretching (ex: Desmosomes).

Which of the following is true of electron microscopes?

C) Electron microscopes use electrons to illuminate the specimen.

Which of the following is true of Carbohydrates?

C) Provides chemical energy, carbon, support, and identity to the cell.

Which cell type would be considered a prokaryote?

B) Archaea.

Which microscope would be most useful for determining the viability of cell populations?

C) Fluorescence Microscopy.

The ___ maintains cell shape and plays key roles in cell division and chromosome segregation

The cytoskeleton maintains cell shape and plays key roles in cell division and chromosome segregation.

Cell size is limited by which of the following?

A) Surface area-to-volume ratio.

True or False? The transmission electron microscope is used to view thin specimens

True.

What is Cell Fractionation?

C) Separates cells into their component parts.

True or False? Not all cells need to be bound by plasma membranes.

F.

True or False? A cell’s bilayer is made of phospholipids with embedded protein molecules.

T.

True or False? Phospholipid bilayers are permeable to most water-soluble (hydrophilic) substances.

F.

The cytoplasm (between the plasma membrane and the central region) contains the _ and _.

The cytoplasm (between the plasma membrane and the central region) contains the cytosol and cytoskeleton.

The ___ maintains cell shape and plays key roles in cell division and chromosome segregation.

The cytoskeleton maintains cell shape and plays key roles in cell division and chromosome segregation.

The ___ is an aqueous solution containing ions, various organic molecules, and organelles.

The cytosol is an aqueous solution containing ions, various organic molecules, and organelles.

What is true regarding prokaryotic cells?

A) Do not have a membrane-bound nucleus.

Which of the following statements is false regarding plasmids?

C) Are essential for survival.

What is true about lysosomes?

B) Contain digestive enzymes that perform acid hydrolases.

What organelle does cellular respiration occur in?

D) Mitochondria.

Which process occurs at the Nucleolus?

C. Ribosomal RNA synthesis.

What is the function of a chaperone protein?

D. Help folding of new proteins.

Storage of the ___ ion is a function of the Sarcoplasmic Reticulum.

Storage of the Ca 2+ ion is a function of the Sarcoplasmic Reticulum.

A cell with high rates of protein synthesis will have elevated amounts of which organelle?

C. Ribosomes.

The nuclear envelope, endoplasmic reticulum, Golgi complex, lysosomes, vesicles, and plasma membrane make up the _.

The nuclear envelope, endoplasmic reticulum, Golgi complex, lysosomes, vesicles, and plasma membrane make up the endomembrane system.

Which is NOT a function of the Endoplasmic Reticulum?

C. Storage.

The endosymbiotic theory suggests that which organelle originated as prokaryotic endosymbionts?

B. Mitochondria.

What are the 3 types of filaments making up the cytoskeleton?

Microtubules, intermediate filaments, microfilaments.

Microtubules are made from _ proteins; Microfilaments are made from _ proteins.

A. Tubulin; actin.

Sacs in the Golgi complex are ; while folds of the Mitochondria are .

Sacs in the Golgi complex are cisternae; while folds of the Mitochondria are cristae.

Three main additions to the Cell Theory (Modern Cell Theory)

DNA is passed between cells during cell division; The cells of all organisms within similar species are mostly the same, both structurally and chemically; Energy flow occurs within cells.

Four basic biomolecules all cells are composed of

Carbohydrates, proteins, lipids and nucleic acids.

Three important parameters for microscopy

Magnification; Resolution; Contrast.

Function of Bright Field Microscopy

Simplest technique; light passes directly through the specimen; often uses stain to enhance contrast.

Function of Phase Contrast Microscopy

Variations of density within the specimen are amplified to enhance contrast in unstained living cells.

Function of Fluorescence Microscopy

Sample is treated with fluorophores so it re-emits light; used for high-resolution imaging of structural components (e.g., DNA) or viability studies.

Function of Confocal Laser Scanning Microscopy (CLSM)

Provides optical sectioning by using a laser and pinhole to block out-of-focus light; used to construct precise 3D images of fixed or live specimens.

Function of Transmission Electron Microscopy (TEM)

Used to view thin sections of specimen (like tissues/molecules); best for viewing internal structure of fixed cells.

Function of Scanning Electron Microscopy (SEM)

Focuses electrons onto the surface of a specimen, providing 3-D images of surface characteristics.

Function of Cryo-electron microscopy

Allows preservation of specimens at very low temps (<-160C) for visualization of structures in their cellular environment without preservatives; used to work out protein makeup and shape.

Cell size limitation concept/process

As a cell grows, volume increases as the cube of its radius while surface area increases as the square of its radius; the surface area becomes insufficient to support the exchange needs (resources/wastes) for the increased volume.

Plasma membrane structure/composition

Phospholipid bilayer with embedded proteins that serves as a selectively permeable barrier; the bilayer is a hydrophobic barrier to water-soluble substances.

Components of the cytoplasm

Contains the cytosol (aqueous solution with ions/molecules/organelles) and cytoskeleton (protein fibers/tubules).

Defining feature of Prokaryotic cells

Absence of a membrane-bound nucleus; DNA lies in the nucleoid region, which has no boundary membrane.

Nucleoid region

Region where the prokaryotic chromosome (single circular DNA molecule) is located; lacks a boundary membrane separating it from the cytoplasm.

Function of plasmids

Extrachromosomal circular DNA molecules containing genes that are generally not required under normal conditions but help cells adapt to unusual circumstances (e.g., antibiotic resistance).

Function of the prokaryotic cell wall/glycocalyx

Provides a tough, fibrous layer of protection, resists osmotic pressure, and aids in adhesion; the glycocalyx is coated with polysaccharides (capsule or slime layer).

Sex Pilus function

Specialized pili that joins bacteria during conjugation (mating) to exchange fragments of DNA (plasmids).

Eukaryotic nucleus function

The administrative center of the cell; contains genetic material (DNA) and directs manufacture of cellular molecules.

Nuclear envelope structure

Double-membrane structure (each a lipid bilayer) that surrounds the nucleus, separating contents from the cytoplasm; perforated by nuclear pores.

Nucleolus function

Distinct region within the nucleus where ribosomal RNA (rRNA) is synthesized and ribosomal subunits are assembled.

Nuclear localization signal (NLS) function

A special, short amino acid sequence on proteins made in the cytoplasm that targets them for transport into the nucleus through nuclear pores.

Fate of proteins made on free ribosomes

May remain in the cytosol, pass into the nucleus, or become part of mitochondria, chloroplasts, or the cytoskeleton.

Fate of proteins made on bound ribosomes

Generally destined for insertion into membranes, packaging within organelles (like lysosomes), or export/secretion from the cell; they follow a special path to the ER and Golgi complex for maturation.