Chapter 4: Cell Structure and Function

how do unicellular organisms reproduction?

a single cell divides and becomes 2 new organisms

How do multicellular organisms grow?

Many cells divide

Why do cells favor a small size?

Small cells have a greater surface area to volume ratio

Do prokaryotic cells have a nucleus?

No

Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell. What evidence can be used to support his claim?

The organelle has a double membrane

What is the effect of not having ATP available to supply energy to this process?

H+ ions will stop moving through the membrane (Metabolic energy such as ATPATP is required for active transport of ions against a concentration gradient.)

The active transport pump used to move sodium ions across the membranes of gill cells in a freshwater fish has each of the following characteristics EXCEPT:

It uses osmosis to carry sodium ions into the cell

Which cell component is not found in prokaryotic cells?

The nuclear envelope

What best explains how the phospholipid bilayer of a transport vesicle contributes to cellular functions?

The phospholipid bilayer allows the vesicle to fuse with the golgi apparatus and the plasma membrane, allowing the exocytosis of proteins

What is the strongest evidence supporting the endosymbiont hypothesis?

Mitochondria have their own DNA and divide independently of the cell

Which cellular components are found in eukaryotic cells but not prokaryotic cells?

The endoplasmic reticulum, mitochondria, and nucleus

What is the difference between rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them?

Rough ER can synthesize and package proteins for export, and smooth ER cannot

How do the rough ER, golgi apparatus, and vesicle work together?

To synthesize and isolate proteins for secretion or for use in the cell

What does the cell theory state?

All living things are made up of cells, cells are the basic units of structure and function in living things, cells come only from preexisting cells because cells are self-producing

What are three basic shapes of prokaryotes?

Spirillum, spirochete, coccus, and bacillus

How is prokaryotic bacteria organized?

Into the cell envelope, the cytoplasm, and the appendages

What is included in the cell envelope?

Plasma membrane, cell well, and glycocalyx

What is the function of the plasma membrane?

regulates which materials enter and leave the cytoplasm

In prokaryotes, what can the plasma membrane form?

Mesosomes (most likely increase the internal surface area for the attachment of enzymes that are carrying on metabolic activities

What is the cell wall?

Maintains the shape of the cell wall

What is the glycocalyx?

Layer of polysaccharides that lie outside the cell wall in some bacteria that aids against drying out and helps bacteria resist a host's immune system

What is the cytoplasm?

Semifluid solution composed of water and inorganic and organic molecules encased in plasma membrane

Where is the DNA of a prokaryote found?

In a single, coiled chromosome that is located in the nucleotid

What are plasmids and what are they used for?

Extra chromosomal pieces of circular DNA that are used as molecular vehicles (vectors) to transport DNA from different organisms

How is it possible to transport DNA from one organism to another?

All life on earth are constructed from the same 4 nucleotides: A, G, C, and T

What are ribosomes?

The site where proteins are made

What is special about cyanobacteria?

They are capable of photosynthesis like plants

What are thylakoids?

Extensive internal membranes that contain chlorophyll and other pigments that absorb solar energy for carbohydrate production

Where are thylakoids found?

In the cytoplasm

Why are cyanobacteria called the "blue green bacteria"?

Some pigment adds a shade of blue, in addition to the green

How do motile bacteria have the ability to propel themselves in water? (hint: which appendage?)

Flagella

What are fimbriae appendages and what do they do?

Small, bristlelike fibers that sprout from the cell surface that attach bacteria to a surface

What do the conjugation pili appendages do?

Rigid tubular structures used by bacteria to pass DNA from cell to cell

Through which process does bacteria reproduce?

Binary fission

What does the plasma membrane separate?

The contents of the cell from the environment

What is the plasma membrane composed of?

A phospholipid bilayer with embedded proteins

How did the mitochondria and chloroplasts come about?

When a large eukaryotic cell engulfed independent prokaryotes

What is the endosymbiotic theory?

Explains how eukaryotic cells may have evolved from prokaryotic cells

Which relationship explains the symbiotic theory?

The mitochondria and chloroplasts arose when a large eukaryotic cell engulfed independent prokaryotes

Which word can best describe the organization of eukaryotic cells?

Compartmentalized

What do membranes do?

Create internal spaces that divide the labor necessary to conduct life functions

What are organelles and what do they do?

Compartments of a eukaryotic cell that carry out specialized functions that allow cell to be more efficient and successful

What are nearly all organelles surrounded by?

A membrane with embedded proteins (many are enzymes)

Where does the production of specific molecules take place? What makes these molecules?

Inside or on the surface of organelles; enzymes embedded in the organelle's membranes make these molecules

How are the specific molecules made by enzymes transported around the cell?

By vesicles (enclose the molecules and keeps them separate from the cytoplasm)

How do vesicles move around?

Through the cytoskeleton (network of protein fibers)

What is the function of the cytoskeleton?

Maintain cell shape and assists with cell movement

Which eukaryotic cell has a cell wall?

Plant cell

What is the function of the nucleus?

Contains genetic info that is passed from cell to cell, specifies info that ribosomes use to carry out protein synthesis, contains instructions for copying itself

Where is the chromatin from the nucleus located?

In the nucleoplasm

How do chromatins become chromosomes?

The chromatins condense and undergo coiling into rodlike structures

When do chromatins become chromosomes?

Just before the cell divides (mitosis)

What do chromatins contain?

DNA, protein, and RNA

Where are genes located?

On chromosomes

What are the three types of RNA produced in the nucleus?

- Ribosomal RNA (rRNA)
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)

Where is ribosomal RNA produced?

The nucleolus

What occurs in the nucleolus?

rRNA joins with proteins to form the subunits of ribosomes

What does messenger RNA (mRNA) do?

Specifies the sequence of amino acids in a protein

What does transfer RNA (tRNA) do?

Recognizes both mRNA and amino acids during protein synthesis

What separates the nucleus from the cytoplasm?

The nuclear envelope

How is the nucleus able to communicate with the cytoplasm?

Through nuclear pores

What do nuclear pores do?

Permit the passage of ribosomal subunits and mRNA out of the nucleus into the cytoplasm and the passage of proteins from the cytoplasm into the nucleus

Where does protein synthesis occur?

Ribosomes

What are the necessary components of a function ribosome?

A large and small ribosomal subunit (each comprised of a mix of proteins and rRNA)

In the nucleus, what is a gene copied into and where is it exported?

A gene is copied into mRNA and is exported through a nuclear pore complex into the cytoplasm

Which component receives the mRNA?

Ribosomes

How are ribosomes able to bind to the endoplasmic reticulum?

If the protein being synthesized by a ribosome begins with a sequence of amino acids called a signal peptide

How do ribosomes bind to the endoplasmic reticulum?

The signal peptide binds a particle, which then binds to a receptor on the ER

What happens when the protein enters the ER?

An enzyme splits off the signal peptide, and the protein ends within the interior of the ER, where it folds into its final shape

What do vesicles do?

Transport molecules from one part of the system to another

What does the rough ER allow proteins to do?

To fold and take on final 3-dimensional shape

Describe the function of the enzymes located in the rough ER

Can add carbohydrate (sugar) chains to proteins (to form glycoproteins)

How does the smooth ER physically differ from the rough ER?

The smooth ER doesn't have attached ribosomes

What does the endomembrane system consist of?

Nuclear envelope, endoplasmic reticulum, golgi apparatus, and several types of vesicles

Describe the function of the smooth ER

Helps in lipid production and transporting molecules to different parts of the cell

True or False: Only the smooth ER forms vesicles that transport molecules to other parts of the cell, notably the Golgi Apparatus

False; Both the rough and smooth ER form form vesicles

At its inner face, what is received by the Golgi Apparatus?

Protein filled vesicles from the rough ER and lipid filled vesicles from the smooth ER

The golgi apparatus has the ability to change or modify which substance?

Change or modify one sugar into another on glycoproteins

What is the golgi apparatus responsible for sorting?

Modified molecules and packaging them into vesicles that depart from the outer face

Which vesicle is produced by the golgi apparatus?

Lysosomes

What do lysosomes do?

Assist in digesting material taken into cell + destroy nonfunctional organelles and portions of cytoplasm

What happens when a lysosome fuses with a vesicle or vacuole?

Lysosomal enzymes are activated and digest the material into simpler subunits that exported into the cytoplasm and recycled by other cell processes

What are lysosomes considered to be?

Specialized vesicles

How and why are organelles within the endomembrane system able to interact?

Their membranes readily fuse together and membrane-associated proteins enable communication and specialized functions

Define secretion

A process by which substances are produced and discharged from a cell, gland, or organ for a particular function in the organism or for excretion.

Which parts of the cell are known to not communicate with the organelles of the endomembrane system?

Peroxisomes and vacuoles of cells

What are peroxisomes?

Membrane-bounded vesicles that enclose enzymes

Describe the course of the enzymes in peroxisomes

Are synthesized by free ribosomes and transported into a peroxisome from the cytoplasm

Describe the function of peroxisomes

Are metabolic assistants to other organelles and are common in cells that synthesize and break down lipids

What are vacuoles?

Membranous sacs that are larger than vesicles

Describe the function of vacuoles

For storage (water, nutrients, waste, etc)

What is a plant cell central vacuole?

A large central vacuole in plant cells that is filled with a cell sap that gives added support to the cell

The plant cell central vacuole maintains what kind of pressure?

Hydrostatic or turgor pressure

What does plant cell central vacuole also store? (another function)

Nutrients and waste products

Name the energy-related vacuoles (specialize in converting energy to a form that can be used by the cell)

Chloroplasts and mitochondria

Which cell contains only the mitochondria?

Animal

Which cell contains both the mitochondria and chloroplasts?

Plant

Describe the role of chloroplasts during photosynthesis

Use solar energy to synthesize carbohydrates

What is the equation for photosynthesis?

Solar energy + CO2 + H2O ------- Carbohydrate + oxygen

What are the components of a chloroplast?

Stroma (semifluid that contains enzymes and thylakoids), thylakoids (disc-like saces that formed from third membrane), and granum (stack of thylakoids)