Cells Cells and Cells

What is the smallest unit of life that can function independently?

Cell

In bacterial cells, the nucleoid is where the cell's ______ congregates.

DNA

What are the tail-like structures indicated by letter A in the picture of the bacterium?

Flagella

______ are flattened membrane sacs within a chloroplast where photosynthetic pigments, such as chlorophyll, are embedded.

Thylakoids

7

flagellum

What type of cell membrane proteins help the body identify its own cells?

recognition proteins

What plant organelle is shown in the image and contains photosynthetic pigments?

Chloroplast

What is a network of sacs and tubules extending off the nuclear envelope and is where proteins and lipids are produced?

Endoplasmic reticulum

Key genetic sequences suggest that archaea are more closely related to members of domain ______ than they are to members of Domain Bacteria.

Eukarya

Protists, including the single-celled organisms Amoeba and Paramecium, belong to domain ______.

Eukarya

Protists, plants, fungi, and animals are organisms in the domain

Eukarya.

The ______ is a series of flattened sacs that sorts and packages materials into vesicles to be sent to the cell membrane.

Golgi apparatus

What English physicist first observed the outlines of cells when he looked at cork from an oak tree?

Hooke

What type of cytoskeleton filament is shown in the picture? (tubulin subunits)

Microtubule

______ cells are the simplest forms of life and lack a nucleus.

Prokaryotic

More powerful microscopes of the nineteenth century allowed ______ to first observe and name nuclei.

Robert Brown

Select all the examples that correctly demonstrate the relationship between surface area and volume.

Root hairs, flat leaves, and feathery gills increase surface area. A large, round cell has a lower surface area to volume ratio than a thin, flat cell. Cellular extensions increase the cell's surface area to volume ratio.

In 1855, who proposed that all cells come from preexisting cells?

Rudolph Virchow

Select the three scientists that proposed the three components of the cell theory in the mid-1800s.

Schwann Schleiden Virchow

Why are ions and polar molecules unable to pass directly through a cell membrane?

The interior of the phospholipid bilayer is hydrophobic.

_____ proteins are embedded in the cell membrane and act as passageways for water-soluble materials into or out of the cell.

Transport

True or false: Bacteria are the most abundant and diverse organisms.

True

True or false: Most cells have a small size that is less than 0.1 mm in diameter to maximize surface area relative to volume.

True

What is a correct description of a confocal microscope?

White or laser light is focused through a lens, and the image passes through a pinhole.

A eukaryotic cell is different from a prokaryotic cell in that it contains

a nucleus.

Select all of the following that describe gap junctions.

allow the coordinated contraction of heart muscle cells protein channels between adjacent animal cells

What type of cell junction is shown in the picture? (sandwich)

anchoring junction

In cell membranes, the phospholipids are arranged into a

bilayer.

Outside the cell wall in the bacterium shown, a layer of polysaccharides called the ______ aids in protection and attachment.

capsule

1 (yellow-colored layer)

cell membrane

4

cell membrane

In bacterial cells, what is the function of flagella?

cell movement

5

cell wall

Select all of the following that describe microtubules.

composed of tubulin subunits can be rapidly lengthened or shortened 23 nanometers in diameter act as tracks for the movement of organelles within cells

anchoring junctions

connect animal cells to the extracellular matrix or to adjacent animal cells in one place

Select all of the following that describe anchoring junctions.

connect cells to the extracellular matrix and to each other in one place hold cells in place and link to the cytoskeleton

Select all of the following that are true about lysosomes.

contain enzymes tagged with sugars can fuse with vesicle carrying debris from outside the cell or damaged organelles enzymes inside the lysosome perform hydrolysis reactions

Select all of the following that are components of the cytoplasm, outside the nuclear membrane.

cytoskeleton ions and enzymes organelles cytosol

The ______ is a protein network that occurs within the cytosol, provides support, and helps form ______.

cytoskeleton; cell to cell connections

2

cytosol

The fluid part of the cell cytoplasm is called

cytosol.

The watery mixture of ions, enzymes, and RNA within the cytoplasm is called the

cytosol.

Select all of the following that are true about peroxisomes.

detoxifies H2O2 dismantle toxins from the blood internal proteins can condense into crystals break down fatty acids

Select all of the following that are functions of lysosomes.

dismantle worm-out organelles breakdown large food particles into smaller subunits lyse captured bacteria

In eukaryotic cilia and flagella, the movement of the protein ______ slides adjacent microtubules against each other and causes bending of the appendage.

dynein

Select ways that cells avoid surface area limitations.

efficient transportation system within cell long or thin shape

What type of microscope allows resolution of objects that are about 5 nanometers in size?

electron

plasma membrane

encloses the cytoplasm and lies just under the secondary cell wall

The ability to do work is called ____

energy

The picture shows a(n) ______ cell.

eukaryotic

Cells that contain membrane-bounded organelles and a nucleus are called

eukaryotic cells.

In animal tissues where cells are not in direct contact with each other, what holds cells together and coordinates cell activities?

extracellular matrix

Select all of the following that are true about Archaea.

found in extreme and moderate environments can occupy same environments as bacteria include methanogens and extremophiles

Select all of the following that describe microfilaments of the cytoskeleton.

function in cell contraction and compression composed of the protein actin help anchor cells to each other

Select all of the following types of cells that usually possess cell walls.

fungi algae plant archaea bacteria

tight junctions

fuse cell membranes of adjacent animal cells, forming a barrier

In eukaryotic cells, the nucleus is an organelle that functions in

housing the cell's DNA.

The portion of the phospholipid bilayer indicated by the circle in the picture is

hydrophobic.

2

inner and outer membranes of chloroplast

1

inner membrane

Cytoskeletal components called _______ filaments are made of different proteins depending upon the cell type and help to maintain cell shape and bind some cells together.

intermediate

What type of cytoskeleton filament is shown in the picture? (protein subunits)

intermediate filament

Select all of the following that are true about prokaryotes.

lack a nucleus most ancient forms of life on Earth simplest types of life

What type of microscope passes light through a transparent or thinly sliced specimen to generate true-color views of cells?

light microscope

What type of cytoskeleton filament is shown in the picture? (Actin molecule)

microfilament

Cytoskeletal components called ______ are long, thin rods of actin protein that are used in muscle contractions, stretching and compression, and anchoring of cells.

microfilaments

Dutch scientist Antony van Leeuwenhoek improved lenses for magnification and used them in devices called

microscopes.

What component of the cytoskeleton is made of tubulin protein subunits and is used in cell division and transportation within cells?

microtubules

2

middle lamella

Cellular respiration extracts energy from food and takes place in the organelle called a

mitochondrion

What eukaryotic organelle is shown in the picture and functions in the production of cellular energy by cellular respiration?

mitochondrion

What structure is depicted by the two layers highlighted in yellow in this picture of the nucleus?

nuclear envelope

In this illustration of a nucleus, what are the small, purple, circular structures?

nuclear pores

The ______ found within the nuclear envelope are lined with specialized proteins that allow the transport of substances into and out of the nucleus.

nuclear pores

What structures allow the passage of regulatory proteins into the nucleus and mRNA molecules out of the nucleus?

nuclear pores

Biological membranes are selectively ______, meaning they allow only specific types of molecules to pass into or out of the cell.

permeable

What organelle protects all eukaryotic cells from toxic substances or toxic by-products of chemical reactions?

peroxisome

In cell membranes, what part of a phospholipid molecule is oriented toward the outside of the bilayer?

phosphate head

6

polysaccharide capsule

Eukarya

possible larger cell size, fatty acids in the cell membrane, and nucleus present

4 (dark green-colored layer)

primary cell wall

Select all of the following that are true about eukaryotic flagella.

prominent in sperm cells anchored by basal body contain microtubules

German biologists Schleiden and Schwann were the first to

propose the cell theory.

In all cells, RNA and ribosomes play a role in the production of ______, which are molecules that carry out all of the cell's work.

proteins

What component of cell membranes functions in a diversity of roles, including recognition, transport, adhesion, and facilitating reactions?

proteins

Select all of the following that are able to move laterally within the cell membrane, giving it the description of a fluid mosaic.

proteins phospholipids

Select all of the following that are components of cell membranes.

proteins steroids phospholipids

Some medicines that treat depression block ______ proteins on brain cell surfaces from absorbing serotonin.

receptor

What type of cell membrane protein binds molecules on the cell's exterior, which triggers a reaction in the cell's interior?

receptor proteins

secondary cell wall

rigid, innermost portion of the cell wall

Proteins to be secreted outside of a eukaryotic cell are formed at ribosomes on the surface of the ______ endoplasmic reticulum.

rough

What structure is colored red in this image of the endomembrane system and has ribosomes covering its exterior?

rough endoplasmic reticulum

Select the three common shapes of bacterial cells.

round rod-shaped spiral

3 (light green-colored layer)

secondary cell wall

1

stroma

Select all of the characteristics of organelles.

studded with membrane proteins surrounded by membranes contain distinct proteins

Select all of the functions of the smooth endoplasmic reticulum.

synthesize lipids house enzymes that detoxify drugs and poisons

Select all of the characteristics of eukaryotic cells.

system of internal membranes larger than prokaryotic cells nucleus

Two types of electron microscopes are ______ electron microscopes, which pass electrons through a specimen, and ______ electron microscopes, which beam electrons over the surface of a metal-coated specimen.

transmission; scanning

What type of cell membrane protein allows molecules and ions to enter or exit the cell?

transport proteins

Select all the roles that membranes play in cells.

transport substances into and out of the cell enclose organelles in eukaryotic cells receive and respond to external stimuli

plasmodesmata

tunnels for the exchange of substances between adjacent plant cells

Put the following steps in order for making a protein that will be exported from a eukaryotic cell, beginning with the first step at the top of the list. Instructions

1. In the nucleus, genes in the DNA that encode the membrane proteinase copied into a messenger RNA (mRNA). 2. The mRNA exits the nucleus through nuclear pores of the nuclear envelope. 3. The mRHA binds to a ribosome of the rough ER and produces a protein, which exits the ER in a vesicle. 4. The vesicle delivers the protein to the Golgi apparatus, where the protein folds and is packaged in a vesicle for export form the cell. 5. The vesicle fuses with the cell membrane and releases the protein to the extracellular environment.

Select all of the following ideas that were added to the cell theory in modern times.

All cells use energy to accomplish cell processes. All cells contain DNA, which is duplicated and passed to new cells when the cell divides.

______ junctions link cytoskeletal filaments of adjacent animal cells in one place, like a rivet.

Anchoring

Using improved lenses incorporated into the first simple microscopes, ______ observed many types of microscopic organisms but also perpetuated the idea of spontaneous generation in late 1600s.

Antony van Leeuwenhoek

Select all of the domains of life that contain prokaryotic cells.

Bacteria Archaea

Select the names of the three domains of life.

Bacteria Archaea Eukarya

What microbiologist discovered key molecular differences between two types of prokaryotes, and following his work, biologists divided life into three domains?

Carl Woese

Select the true statement describing how DNA in the nucleus is used to specify protein production by the cell.

DNA is copied into mRNA in the nucleus, and the mRNA is used outside the nucleus to make proteins.

3

DNA within matrix

In a cell, ______ is the genetic information of the cell, and RNA plays a role in the production of ______.

DNA; proteins

Domain ______ is eukaryotic with nuclei and membrane-bound organelles, whereas domains ______ and ______ are prokaryotic without nuclei or other membrane-bound organelles.

Eukarya; Archaea; Bacteria

Domain Archaea is more closely related to domain ______ than to the prokaryotic domain, ______.

Eukarya; Bacteria

Select the organelles that are involved in the production of milk proteins to be secreted by mammary gland cells in animals called mammals.

Golgi apparatus nucleus endoplasmic reticulum

In this picture of the endomembrane system, the structure in the black circle indicated by the arrow is called the

Golgi apparatus.

Lysosomes originate from vesicles that bud from the ______, and the enzymes contained in lysosomes are synthesized in the ______.

Golgi apparatus; rough ER

In 1859, French chemist and microbiologist ______ disproved spontaneous generation of cells, which added evidence to support the cell theory.

Louis Pasteur

Select all of the following that are examples in which the ratio of surface area to volume of cells is increased.

Nerve cells are long and thin. Amoebas have extensions of their cell membrane. Paramecia are horizontally flattened in shape.

______ are a category of plant organelles that contain their own DNA and ribosomes and can convert to many functions.

Plastids

_____ proteins bind to molecules and ions on the outside of the cell, triggering a reaction on the inside of the cell.

Receptor

Select the three components of the cell theory devised in the mid-1800s.

The cell is the fundamental unit of all life. All organisms are made of one or more cells. All cells originate from preexisting cells.

Select all of the following that correctly describe plant organelles called plastids.

They contain their own DNA and ribosomes. Some assemble and store starch. Some, such as chloroplasts, synthesize pigments.

Select all of the following that are present at the connection between normal cells of multicellular organisms.

a way for cells to adhere to one another ways that cells can communicate with each other

Enzymes in the lysosomes function at a more ______ pH than the cytoplasm, which means the enzymes only function within the enclosed lysosome, unless all of a cell's lysosomes burst at once.

acidic

Proteins on the surfaces of cell membranes which enable cells to stick to other cells are called ______ proteins.

adhesion

What type of cell membrane protein enables neighboring cells to stick to each other?

adhesion proteins

Select all of the following that are functions of the cytoskeleton in the cell.

aid for cell division structural support transportation

As described in this chapter's Investigating Life essay, some bacteria contain magnetosomes, which allow bacteria to

align with Earth's magnetic field.

What type of prokaryotes are most closely related to eukaryotes?

archaea

If an mRNA specifies a protein to be used in the cell membrane or to be secreted from the cell, this protein is made on ribosomes that

attach to the endoplasmic reticulum.

Spiral or corkscrew, round, and rod-shaped are all common shapes of

bacteria.

The outer polysaccharide layer colored green in the image of a bacterium and indicated by the arrow is called the

capsule.

Enzymes in the Golgi apparatus can synthesize and attach ______ to proteins and lipids, forming glycoproteins and glycolipids.

carbohydrates

In eukaryotic cells, what is the function of chloroplasts?

carry out photosynthesis

A(n) ____ is the smallest and most basic unit of life and can function as one or many working together.

cell

All living things consist of one or more ______.

cell

The ____ theory states that all life is composed of one or more cells, which are the fundamental units of all life.

cell

The rigid ______ of most bacterial cells surrounds the cell membrane, protecting the cell and giving the cell shape.

cell wall

What surrounds the cell membrane of most bacteria and provides structure and protection?

cell wall

plant cell

cell wall and chloroplasts present

What cell shape has the most efficient exchange of materials between the cell's interior and exterior?

cell with more surface area relative to volume

What did Robert Hooke call the little units he observed when he viewed cork under lenses of glass?

cells

Whether bacterium or blue whale, every organism is made of

cells.

What component of plant cell walls aligns into crisscrossing fibers that provide great strength?

cellulose

As most plant cells lack lysosomes, what organelle in plant cells performs the functions of recycling and degradation of molecules and old organelles?

central vacuole

What plant cell organelle can occupy up to 90% of the cell volume and can exert turgor pressure against the cell membrane when it acquires water?

central vacuole

Each centrosome in animal cells contains two ______, which form basal bodies of flagella and cilia and spindle fibers of chromosomal division.

centrioles

animal cell

centrioles present

In animal cells, structures called ______ are microtubule-organizing centers that contain the centrioles.

centrosomes

gap junctions

channels for the exchange of substances between adjacent animal cells

The organelle that is the site of photosynthesis in plant cells is the _______ , which is a type of plastid.

chloroplast

Select all of the following that are present in plant cells but not in animal cells.

chloroplasts cell wall

Select all the organelles that are thought to have arisen by endosymbiosis.

chloroplasts mitochondria

What is a steroid molecule that is found in animal cell membranes and that maintains membrane fluidity?

cholesterol

Some protists, like Paramecium, are able to move through a watery environment with thousands of short extensions on the cell called ______

cilia

Short, numerous, hairlike structures that surround some cells like a fringe, are powered by microtubules, and have coordinated movements are called

cilia.

Although both are involved in movement and arise from basal bodies of microtubules,________ are short and numerous extensions, whereas __________ are longer and occur singly or in pairs.

cilia;flagella

4--folds of inner membrane

cristae

The folds of the inner membrane of a mitochondrion, called ______, contain the enzymes for cellular respiration.

cristae

The ______ includes all of the cell contents between the nucleus and the cell membrane.

cytoplasm

Select all of the following that are present in both prokaryotic cells and eukaryotic cells.

cytoplasm RNA ribosomes DNA

Select all of the following that are present in bacterial cells.

cytoplasm ribosomes enzymes DNA

The two-layered nuclear envelope separates the nucleus of a cell from the

cytoplasm.

Defective proteins, such as ankyrin and dystrophin, and impact injuries to brain cells can disrupt the normal structural support provided by the ______ and cause the cells to degenerate.

cytoskeleton

In Duchenne muscular dystrophy, cells lack the protein dystrophin, which is a component of the ______ in muscle cells.

cytoskeleton

The microfilaments, intermediate filaments, and microtubules shown in the picture comprise the ________, which is a network of proteins that provide a structural framework within the cell.

cytoskeleton

What is the network of protein fibers and tubules inside the cell that provides support and aids in cell division and movement?

cytoskeleton

The internal membranes of several organelles are interconnected and form the ______ system of a eukaryotic cell.

endomembrane

Peroxisomes are organelles that originate at the ______ and contain enzymes that dispose of toxic substances.

endoplasmic reticulum

What theory describes how ancient organisms engulfed bacterial cells and, instead of being digested, the bacterial cells became organelles within the host cells?

endosymbiosis

What types of cells are likely to contain thousands of mitochondria?

energy-consuming muscle cells

Modern cell theory added three more ideas to the original cell theory, including that all cells have the same chemical composition, all cells use ______, and all cells contain ______ as the genetic information that is duplicated and passed on when cells divide.

energy; DNA

Organelles called lysosomes contain ______ that break down food particles, old organelles, and other cellular debris.

enzymes

Proteins that increase the speed of chemical reactions on the cell membrane and in other parts of the cell are called _______

enzymes

What type of membrane protein speeds up chemical reactions?

enzymes

Outside of the cell membrane in many animals cells is the ______, which holds the cells together and coordinates some activities between cells.

extracellular matrix

What is the function of mitochondria in eukaryotic cells?

extract energy from food

What is the function of membrane proteins that are enzymes?

facilitate chemical reactions

Imagine an inflating balloon. As the balloon grows, its volume increases _____ than its surface area.

faster

In some types of bacteria, appendages called ______ rotate like a propeller and allow movement forward or backward.

flagella

Select all of the locomotory structures that consist of shaft of microtubules linked together by dynein protein.

flagella cilia

What eukaryotic cellular extension is long, has a whiplike motion that propels cells, and usually occurs singly or in pairs?

flagellum

The cell membrane can be described as a(n) ______ mosaic because many of the diverse components can move freely within the cell membrane.

fluid

A protein channel that links the cytoplasm of two animal cells and allows the exchange of ions, nutrients, and small molecules between the cells is called a(n) _____ junction.

gap

The cell wall openings in plant cells called plasmodesmata are most similar to ______ junctions in animal cells.

gap

Select all of the functions of the bacterial cell wall.

give the cell its shape protect the cell prevent the cell from bursting

A small, cube-shaped object has a surface area to volume ratio that is ______ that of a large, cube-shaped object.

greater than

Select all of the following that describe intermediate filaments of the cytoskeleton.

have a diameter of 10 nanometers form an internal scaffold in the cytosol

Peroxisomes contain enzymes that detoxify ______, a highly reactive compound that is produced by some chemical reactions in the cell and can damage the cell by causing oxygen free radicals.

hydrogen peroxide

The head of a phospholipid is ______, meaning its polar covalent bonds attract water, but the tails of a phospholipid are ______ and thus water-insoluble.

hydrophilic; hydrophobic

What is the function of recognition proteins in the plasma membrane?

identify the cell as belonging to the body and a certain tissue type

The long, thin ears of desert mammals are adaptations that ______, which facilitates the loss of body heat.

increase surface area

The ______ microscope is ideal for viewing living cells that are between 200 nanometers and 1 millimeter in size.

light

If secondary cell walls are present in plant cells, they are located inside primary cell walls and are more rigid due to the presence of the polymer

lignin.

Lysosomes are often required to process ______, which reach toxic levels in the brain cells of people with malfunctioning lysosomes (a condition called Tay-Sachs disease).

lipids

Select all of the following that are able to pass freely through the phospholipid bilayer.

lipids small nonpolar molecules O2 and CO2

Select types of cells that have relatively more lysosomes.

liver cells white blood cells

What organelle of the endomembrane system breaks down debris, food, and old cell parts with special dismantling enzymes?

lysosome

Select all of the cell parts that are involved in the endomembrane system.

lysosomes endoplasmic reticulum nuclear envelope vacuoles Golgi apparatus

Within the nucleus, protein synthesis information in DNA is copied into ______, which then exit the nucleus through nuclear pores.

mRNA molecules

Select all of the following that are found in mitochondria.

matrix enzymes ribosomes DNA

All cells have a cell _____ that surrounds the cytoplasm and forms a boundary between the cell and its environment.

membrane

Organelles carry out specialized functions in the cell and are enclosed by

membranes.

Archaeans called methanogens use carbon dioxide and hydrogen from the environment and produce ______ as a byproduct.

methane

Select all of the following that differ between domains Bacteria and Archaea.

molecules that compose the cell membranes evolutionary relationship to eukaryotes chemical composition of flagella

Select all of the following that correctly describe Archaean cells.

most have cell walls lack nuclei and organelles can have flagella

The area within the cytoplasm of a prokaryotic cell where the circular DNA molecule is found is called the ______ and is not bounded by a membrane.

nucleoid

3

nucleoid region with DNA

In prokaryotic cells, DNA congregates in an area called the

nucleoid.

Inside the nucleus of a eukaryotic cell, the subunits of ribosomes are assembled in the

nucleolus.

What prominent structure in the eukaryotic cell is highlighted by blue color in the picture?

nucleus

In eukaryotic cells, the DNA that codes for the cell's proteins is stored in a membrane-bounded organelle called the

nucleus.

Scottish surgeon Robert Brown was the first to observe a roughly circular structure in plant cells that he called the

nucleus.

The endomembrane system is a coordinated system of ______ in eukaryotic cells.

organelles

What feature enables eukaryotic cells to keep biochemicals and related structures in close proximity and increase efficiency within a relatively large cell volume?

organelles

Within the cytoplasm of eukaryotic cells, there are multiple specialized compartments called

organelles.

2

outer membrane

primary cell wall

outer, more flexible layer of the cell wall

All cells are surrounded by cell membranes, also called plasma membranes, that separate the cytoplasm from the

outside environment.

The enzymes in one lysosome could not digest a cell because the ______ of the lysosome is much ______ than the neutral cytoplasm, and therefore the lysosome enzymes would not be able to function fully in the cell cytoplasm.

pH; more acidic

The cell membrane is composed of a type of lipid molecule called a(n) ______, which has two fatty acids and a phosphate group extending from a glycerol molecule.

phospholipid

The image shows a(n)

phospholipid bilayer of a membrane.

The molecule shown in the picture is a

phospholipid.

What molecules are key components of cell membranes and are arranged in bilayers to form membranes?

phospholipids

What types of plant cells are packed with chloroplasts?

photosynthesizing leaf cells

Select all of the following that are found in chloroplasts.

photosynthetic pigments stroma ribosomes thylakoids DNA

Tunnels called ______ occur in the cell walls of two adjacent plant cells and allow the cells to communicate and exchange materials with each other.

plasmodesmata

What plant structure can play a role in the spread of viruses from cell to cell?

plasmodesmata

Water, nutrients, hormones, and some organelles flow between adjacent plant cells through special channels in the cell wall called

plasmodesmata.

middle lamella

region where adjacent cell walls meet

Select all of the following that are roles of cell walls.

regulate cell volume help determine cell specialization provide shape

The endoplasmic ______ is a network of membranes originating at the nuclear envelope and winding through the cell.

reticulum

SEM

reveals topography of specimen's surface

What cell structure binds to mRNA coming from the nucleus and manufactures proteins?

ribosome

1

ribosomes

The nucleolus is a dense spot in the nucleus where components of ______ are assembled.

ribosomes

TEM

shows internal features of specimen; highest resolution electron microscope

Bacteria

small cell size, fatty acids in the cell membrane, and prokaryotic

Archaea

small cell size, nonfatty acid lipids in the cell membrane, and prokaryotic

Lipids, detoxifying enzymes, and membrane components are produced and stored in the ______ endoplasmic reticulum.

smooth

What structure is indicated by the arrow in this picture of the endomembrane system and lacks ribosomes covering the exterior?

smooth endoplasmic reticulum

Select all of the following that are true about organisms in Domain Bacteria.

some are used to make pharmaceuticals Earth's oldest organisms important decomposers and producers some live in human intestines and help with digestion

Lipids called ______, which include cholesterol, are membrane components that aid in membrane fluidity.

steroids

What type of organic molecules help maintain membrane fluidity as temperature fluctuates?

steroids

In mammals, mitochondrial DNA is inherited from

the female parent only.

Based on Carl Woese's work, biologists recognized _____ domains of life.

three

3

thylakoids

In animal cells, cell junctions called ______ junctions form barriers between cells that prevent leaking of fluids and water-soluble molecules.

tight

What type of cell junction is shown in the picture?

tight junction

Which of the following types of microscopes has the highest magnification and can resolve objects less than 1 angstrom apart?

transmission electron microscope

Select all of the following that are components of phospholipid molecules, which are the main constituents of cell membranes.

two fatty acids glycerol molecule phosphate group

Select all of the following that describe electron microscopes.

use beam of electrons instead of light expensive to build and operate usually require that specimen be killed provide greater magnification than light microscopes

The protein produced by a free ribosome (left panel) will most likely be ______, while the protein produced by a ribosome attached to the rough ER's membrane (right panel) will most likely be ______.

used in the cytosol; used in the cell membrane

Select all of the following that describe compound microscopes.

uses two or more lenses to focus visible light type of light microscope commonly used in biology lab courses

Plant cells have large central ______ where water, salts, and sugars are stored and where materials are broken down and recycled with enzymes similar to lysosomes in animal cells.

vacuoles

In the Golgi apparatus, proteins are sorted and packaged into ______ that deliver the proteins to their destinations.

vesicles

What are the structures indicated by the arrows in the picture that have pinched off the Golgi apparatus and will deliver their contents to another part of the cell?

vesicles

Membranous spheres that transport materials inside the cell as part of the endomembrane system are called

vesicles.

Membrane proteins synthesized in the ER are transported in ______ to the ______, where the proteins will complete their folding and be packaged for export to the cell membrane.

vesicles; Golgi apparatus

Turgor pressure in plant cells results from the expansion of the central vacuole as it fills with

water.

Select all of the following that are contained within a plant's central vacuole.

weak acids water and salts degrading enzymes pigments