CH 4

The net diffusion rate of substances in the cytoplasm of a cell is so slow that the diffusion distances must be very small, otherwise, cells would be unable to distribute nutrients within a cell, or remove wastes that are produced.

TRUE

Mitochondria is able to take energy from food molecules and store it in high-energy bonds of ATP.

TRUE. This process is done utilizing a series of enzymes within the intermembrane compartment.

A scientist found an unusual organism deep in the crust of the Earth, to find out if its prokaryotic or eukaryotic, which type of test is needed?

Test for microtubule proteins, because only eukaryotes have microtubules.

Mitochondria capture chemical energy gained by breaking down sugars using oxygen and use that energy to produce ATP.

The ATP can then provide energy for cellular processes such as muscle contraction.

How does an organelle allow single-celled eukaryotes to survive in fresh water and not burst due to the influx (in-flow) of fresh water?

The contractile vacuole expels water from the cell. The contractile vacuole is the organelle that collects and eliminates the excess influx (in-flow) of water.

Lysosomes contain very powerful digestie enzymes that can break down proteins, carbohydrates, and other molecules. Why don't these enzymes digest the cell itself?

The enzymes are separated from the cytoplasm by the lysosomal membrane so that they do not harm the cell.

Imagine that you are running for three blocks, describe what oxygen is used for in your cells

The mitochondria in my muscle cells need this extra oxygen to break down sugars and produce the energy I need to run.

Viruses are not considered to be alive.

True, based on the cell theory.

The following generalization can be made about cytoskeleton:

Various cytoskeletal elements are needed in the performance of numerous essential cellular functions.

Chromosome

a DNA double helix together with proteins that help to organize and regulate the use of the DNA.

ribosome

a complex consisting of two subunits, each composed of ribosomal RNA and protein, found in the cytoplasm of cells or attached to the endoplasmic reticulum, that is the site of protein synthesis, during which the sequence of bases of messenger RNA is translated into the sequence of amino acids in a protein.

contractile vacuole

a fluid-filled vacuole in certain protists that takes up water from the cytoplasm, contracts, and expels the water outside the cell through a pore in the plasma membrane.

microtubule

a hollow, cylindrical strand, found in eukaryotic cells, that is composed of the protein tubulin; part of the cytoskeleton used in the movement of organelles, cell growth, and the construction of cilia and flagella.

central vacuole

a large, fluid-filled vacuole occupying most of the volume of many plant cells; performs several functions, including maintaining turgor pressure

cell wall

a layer of material, normally made up of cellulose or cellulose-like materials, that is outside the plasma membrane of plants, fungi, bacteria, and some protists.

flagellum

a long, hairlike extension of the plasma membrane; in eukaryotic cells, it contains microtubules arranged in a 9 + 2 pattern. The movement of flagella propel some cells through fluids.

lysosome

a membrane-bound organelle containing intracellular digestive enzymes.

Organelle

a membrane-bound structure, found in the cytoplasm of eukaryotic cells, that performs a specific function.

food vacuole

a membranous sac within a cell in which food is enclosed. Digestive enzymes are released into the vacuole, where intracellular digestion occurs.

deoxyribonucleic acid DNA

a molecule composed of deoxyribose nucleotides; contains the genetic information of all living cells.

centriole

in animal cells, a short, barrel-shaped ring consisting of nine microtubule triplets; a pair of centrioles is found near the nucleus and may play a role in the organization of the spindle; centrioles also give rise to the basal bodies at the base of each cilium and flagellum that give rise to the microtubules of cilia and flagella.

plastid

in plant cells, an organelle bounded by two membranes that may be involved in photosynthesis (chloroplasts), pigment storage, or food storage.

Prokaryotic cells do not contain

internal membranes.

Lysosomes are involved in

intracellular digestion.

The SER (Smooth Endoplasmic reticulum) is the site of

lipid synthesis.

The "powerhouse" of the cell, it converts food to energy

mitochondria.

Genetic directions from DNA are transcribed as RNA, which is moved through the

nuclear pores to the cytoplasm, where it is used for the translation of protein.

Prokaryotic DNA is organized into a region known as a

nucleoid.

Nuclear pores are the passageways through which most substances, including RNA, move to enter or leave the

nucleus.

Where are proteins that are going to be exported from the cell synthesized?

on the RER (Rough Endoplasmic Reticulum). Proteins that are going to be exported are synthesized on the RER by the attached ribosomes.

intermediate filament

part of the cytoskeleton of eukaryotic cells that is composed of several types of proteins and probably functions mainly for support.

microfilament

part of the cytoskeleton of eukaryotic cells that is composed of the proteins actin and (in some cases) myosin; functions in the movement of cell organelles and in locomotion by extension of the plasma membrane.

chlorophyll

pigment found in chloroplasts that captures light energy during photosynthesis; chlorophyll absorbs violet, blue, and red light but reflects green light.

The following cells contain ribosomes:

plant cells, animal cells, bacterial cells, mitochondria, and chloroplasts.

Mitochondria are needed for

production of cellular energy.

bacteria or bacterium

prokaryotes that are members of the domain Bacteria, one of the three domains of living organisms; only distantly related to members of the domain Archaea

Ribosomes are the site of

protein synthesis in the cell.

ribonucleic acid

a molecule composed of ribose nucleotides, each of which consists of a phosphate group, the sugar ribose, and one of the bases adenine, cytosine, guanine, or uracil; involved in converting the information in DNA into protein; also the genetic material of some viruses.

eukaryotic

referring to cells of organisms of the domain Eukarya (plants, animals, fungi, and protists). Eukaryotic cells have genetic material enclosed within a membrane-bound nucleus and contain other organelles.

Prokaryotic

referring to cells of the domains Bacteria or Archaea. Prokaryotic cells have genetic material that is not enclosed in a membrane-bound nucleus; they also lack other membrane-bound organelles.

The cell theory states that

all living things are composed of cells.

nuclear pore complex

an array of proteins that line pores in the nuclear membrane and control which substances enter and leave the nucleus.

mitochondrion

an organelle, bounded by two membranes, that is the site of the reactions of aerobic metabolism.

The smallest type of cell is a mycoplasma, which has a diameter between 0.1 micrometer and 1.0 micrometer. Mycoplasmas most likely are

bacteria.

Chloroplasts use light energy to make

carbohydrates.

Lysosomal enzymes are able to digest

cellular proteins and other molecules.

The endoplasmic reticulum (ER) is needed for

synthesis of proteins, hormones, and lipids, along with detoxification.

Sorting and modification of proteins is an important function of

the Golgi apparatus. The Golgi apparatus removes protein cargo from the endoplasmic reticulum and then modifies it and sorts it into vesicles that are targeted to different destinations, including the plasma membrane and lysosomes.

The basic unit of life is

the cell, all life is made up of cells.

What organelles are found in animal cells, but are absent in plan cells?

centrioles. Centrioles produce microtubules of cilia and flagella, and those that form the spindle during animal cell divison.

What originated by endosymboisis?

chloroplasts and mitochondria. Biologist believe that both chloroplasts and mitochondria evolved from prokaryotic bacteria that became part of ancestral eukaryotic cells.

RNA is NOT a component of

chromosomes.

Prokaryotic cells process a single molecule of

circular DNA, but no definable membrane-enclosed nucleus.

What do we call the fluid in which all cellular organelles are suspended?

cytoplasm. The fluid inside the plasma membrane and outside the nucleus is considered cytoplasm.

nucleolus

the region of the eukaryotic nucleus that is engaged in ribosome synthesis; consists of the genes encoding ribosomal RNA, newly synthesized ribosomal RNA, and ribosomal proteins.

cell theory

the scientific theory stating that every living organism is made up of one or more cells; cells are the functional units of all organisms; and all cells arise from preexisting cells.

Prokaryotic cells are

very small, usually less than 5 mm in diameter.

A nuclear envelope is found ONLY within eukaryotic cells.

TRUE

Molecules are manufactured in the ER, then packaged in the Golgi, and distributed to the membrane, when this is their final destination.

TRUE

Nuclei are characteristic of EUKARYOTIC cells.

TRUE

Only Eukaryote cells have a nucleus, but all cells have DNA.

TRUE

Both eukaryotes and prokaryotes have phospholipids in their plasma membrane.

True

Lysosomal enzymes are NOT secreted from the cell, they carry on their digestive functions inside the lysosome.

True

Only Eukaryote cells have microtubules.

True

Proteins are components of cells so they are not considered to be alive.

True

Ribosomes contain RNA and are present in ALL cells.

True

The nucleus contains the genetic material of the cell, although mitochondria do have their own DNA.

True

Plasmids are located in the

CYTOPLASM of PROKARYOTIC cells.

Nucleoli are structures within the nuclei of

EUKARYOTIC cells.

Why are living cells limited to remaining microscopic in size?

Exchanges of substances at the membrane surface would take too long to diffuse throughout the interior of the cell.

If the nucleus is the control center of the cell, how is information encoded and shipped to the cytoplasm?

It is encoded and shipped by RNA.

How do molecules such as proteins and RNA enter into or exit from the nucleus?

Molecules move through pores in the nuclear envelope. Large pores made of proteins provide channels through which large molecules and even larger particles can enter into or exit from the nucleus.

Which structures are found in ALL cells?

Plasma membranes and ribosomes.

The nucleolus is the site of

RNA synthesis.

Which organelle would you expect to be in abundance in the liver of a drug addict?

Smooth Endoplasmic Reticulum (SER) because the enzymes for detoxification of drugs and alcohol are housed in the smooth endoplasmic reticulum.

What is the correct order in which newly synthesized proteins are delivered to the plasma membrane?

They are delivered from: -Endoplasmic Reticulum to the -Golgi apparatus to the -plasma membrane.

In certain types of genetic engineering, DNA is injected into the nucleus of a recipient animal cell. What is the fewest number of membranes that must be pierced by the microscopic needle in order to inject the DNA?

Three, you must pass through the plasma membrane and both membranes of the nuclear envelope.

cytoskeleton

a network of protein fibers in the cytoplasm that gives shape to a cell, holds and moves organelles, and is typically involved in cell movement.

cilium

a short, hair-like projection from the surface of certain eukaryotic cells that contains microtubules in a 9 + 2 arrangement. The movement of cilia may propel cells through a fluid medium or move fluids over a stationary surface layer of cells.

Chromosomes consist of

a single DNA double helix wound around proteins. Proteins and DNA.

Golgi apparatus

a stack of membranous sacs, found in most eukaryotic cells, that is the site of processing and separation of membrane components and secretory materials

basal body

a structure derived from a centriole that produces a cilium or flagellum and anchors this structure within the plasma membrane

endoplasmic reticulum

a system of membranous tubes and channels in eukaryotic cells; the site of most protein and lipid synthesis.

vacuole

a vesicle that is typically large and consists of a single membrane enclosing a fluid-filled space.

Mitochondria releases water

during energy production.

Prokaryotic cells do not contain

endoplasmic reticulum.

Mitochondria are involved in

energy metabolism.

Cytoskeleton performs many

functions for the cell.

Chromosomes contain DNA, which provides the

genetic directions to synthesize RNA.

Chromatin

the complex of DNA and proteins that makes up eukaryotic chromosomes.

nuclear envelope

the double-membrane system surrounding the nucleus of eukaryotic cells; the outer membrane is typically continuous with the endoplasmic reticulum.

The organelles that are part of the internal membrane system of eukaryotic cells are

the endoplasmic reticulum, Golgi apparatus, and lysosomes.

cytoplasmic fluid

the fluid portion of the cytoplasm; the substance within the plasma membrane exclusive of the nucleus and organelles; also called cytosol.

endosymbiont hypothesis

the hypothesis that certain organelles, especially chloroplasts and mitochondria, arose as mutually beneficial associations between the ancestors of eukaryotic cells and captured bacteria that lived within the cytoplasm of the pre-eukaryotic cell

nucleoid

the location of the genetic material in prokaryotic cells; not membrane enclosed

cytoplasm

the material contained within the plasma membrane of a cell, exclusive of the nucleus.

nucleus - cellular

the membrane-bound organelle of eukaryotic cells that contains the cell's genetic material.

chloroplast

the organelle in plants and plantlike protists that is the site of photosynthesis; surrounded by a double membrane and containing an extensive internal membrane system that bears chlorophyll.

plasma membrane

the outer membrane of a cell, composed of a bilayer of phospholipids in which proteins are embedded.

The difference between smooth ER (SER- smooth endoplasmic reticulum) and rough ER (Rough Endoplasmic Reticulum) is

the presence of ribosomes on the RER. The ribosomes on the surface of RER give it its rough appearance.