Bio 101: Chapter/Lab 4

Where is a bacterial cell's DNA found?

nucleoid region

endosymbiont theory

-an early ancestor of eukaryotic cells engulfed a prokaryotic cell which formed an endosymbiont relationship with its host -host cell and endosymbiont merged into a single organism, a eukaryotic cell with a mitochondrion or a chloroplast

extracellular matrix (ECM) of animal cells

-animals lack cell walls but are covered by an elaborate ECM -made up of glycoproteins like collagen, proteoglycans, and fibronectin -ECM proteins bind to receptor proteins in the plasma membrane called integrins

plasmodesmata in plant cells

-channels that perforate plant cell walls -through plasmodesmata, water and small solutes (sometimes proteins and RNA) can pass from cell to cell

Golgi apparatus

-consists of flattened membranous sacs called cistern (resembles stack of pita) -modifies products of ER, manufactures certain macromolecules, and sorts/packages materials into transport vesicles

electron microscope disadvantages

-difficult to use and lengthy to prepare sample -uses toxic substances -sample must be dead -cannot observe processes -picture is black and white -small field of view

nucleus

-eukaryotic cell's genetic instructions (genes) are housed here and carried out by ribosomes -flow of info always goes DNA->RNA->Proteins -usually most conspicuous organelle -nuclear envelope: outermost covering, separates nucleus from cytoplasm -pores: regulate entry and exit of molecules (i.e. RNA and proteins) from nucleus -nuclear lamina: maintains shape of nucleus, composed of protein -in nucleus, DNA is organized into discrete units called chromosomes (one long DNA molecule associated with proteins) -DNA and proteins of chromosomes are chromatin -nucleolus is within nucleus and is site of rRNA synthesis

cell walls of plants

-extracellular structure that distinguishes plant cells from animal cells -prokaryotes, fungi, and some protists also have cell walls -wall protects plant cell, maintains its shape, and prevents excessive uptake of water -plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein -plant cell walls can have multiple layers -plasmodesmata are channels between adjacent plant cells that are used for free communication of nutrients and water

vacuoles

-large vesicles derived from ER and Golgi -food vacuoles: formed by phagocytosis -contractile vacuoles: pump excess water out of cells, found in many freshwater protists -central vacuoles: hold organic compounds and water, found in many mature plant cells -certain vacuoles in plants and fungi carry out enzymatic hydrolysis like lysosomes

ribosomes

-made of ribosomal RNA and protein -carry out protein synthesis in 2 locations: cytosol (free ribosomes) and on outside of ER or nuclear envelope (bound ribosomes) -ribosome is laminator: insert paper (~mRNA) and from other end u get product (~protein)

lysosomes

-membranous sac of hydrolytic enzymes that can digest macromolecules -can hydrolyze proteins, fats, polysaccharides, and nucleic acids -lysosomal enzymes work best in acidic environment inside lysosome -some types of cells can engulf another cell by phagocytosis, forms food vacuole -lysosome fuses w food vacuole and digests the molecule -also use enzymes to recycle cell's own organelles and macromolecules: autophagy

extracellular components

-most cells synthesize and secrete materials that are external to the plasma membrane -these extracellular materials are involved in many cellular functions: cell walls in plant cells, ECM in animal cells, and cell junctions

cilia and flagella

-movement of materials over cell surface -microtubules control the beating of cilia and flagella: microtubule-containing extensions projecting from some cells -flagella are limited to one or a few per cell, while cilia occur in large numbers on cell surfaces -cilia and flagella also differ in their beating patterns

cell junctions

-neighboring cells in animal or plant often adhere/interact/communicate through direct physical contact -several types of intercellular junctions that facilitate this: 1. plasmodesmata 2. tight junctions 3. desmosomes 4. gap junctions

cytoskeleton

-network of fibers extending throughout cytoplasm -organizes cell's structures and activities, anchoring many organelles -helps to support cell and maintain its shape interacts with motor proteins to produce motility -inside cell, vesicles and other organelles can "walk" along the tracks provided by cytoskeleton

plasma membrane

-selective barrier that regulates entry/exit of various things in the cell -phospholipid bilayer -proteins embedded in this layer

mitochondria

-sites of cellular respiration -enveloped by a double membrane -contain free ribosomes and circular DNA molecules -grow and reproduce somewhat independently in cells -present in nearly all eukaryotic cells -have smooth outer membrane and inner membrane folded into cristae -inner membrane creates 2 compartments: intermembrane space and mitochondrial matrix -some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix -cristae present a large surface area because of its folds for enzymes that synthesize ATP

chloroplasts

-sites of photosynthesis -found in plants and algae -enveloped by a double membrane -contain free ribosomes and circular DNA molecules -grow and reproduce somewhat independently in cells -found in leaves and other green organs of plants and in algae -structure: thylakoids: membranous sacs which are stacked to form a granum, and stroma: internal fluid

rough ER

-studded w ribosomes -serves as synthesis site of secreted proteins (ex: pancreatic cells secrete insulin (a protein hormone that controls blood level) so pancreatic cells have extensive RER) -most secretory proteins are glycoproteins (proteins covalently bonded to carbs) which takes place in ER -from RER the secretory protein travels in membrane wrapped transport vesicles -RER serves as membrane factory for cell. when needed RER membrane expands and portions are transferred where required

smooth ER

-synthesizes lipids, metabolizes carbs, detoxifies drugs and poisons, stores calcium ions (Ca+) -since SER is involved w drug detox, the liver cell of drug/substance abuser will show extensive presence of SER -athlete's muscle cells will show extensive ER as it stores Ca+ which is important in muscle movement

three main types of fibers make up the cytoskeleton

1. microtubules: thickest 2. microfilaments: (actin filaments) thinnest 3. intermediate filaments: diameters in a middle range

The _____________ is the ability to distinguish between two points that are very close together to one another. The ____________ is the ability to enlarge an object relative to its actual size.

1. resolving power 2. magnifying power

tight junctions, desmosomes, gap junctions

1. tight junctions: A type of intercellular junction in animal cells that prevents the leakage of material between cells. 2. desmosomes: A general cell junction, used primarily for adhesion. 3. gap junctions: A type of intercellular junction in animals that allows the passage of materials between cells.

1 meter = _____ centimeters. 1) 100 2) 1,000,000,000 3) 1,000 4) 1,000,000,000,000 5) 1,000,000

100

How many eyepieces does the stereoscopic dissecting microscope contain?

2

If the ocular on a compound light microscope has a magnification of 10x, what is the total magnification with a 5x objective? and with a 45x objective? 40X; 400X 50X; 450X 40X; 500X 5X; 45X

50X; 450X

If you are viewing through compound microscope with total magnification of 550X, then the objective lens has power of [X].

55

In order to examine the organelles found within the cells of the thorax, which of the two microscopes is better to use?

A compound light microscope; they are the best for viewing small and thin specimens

resolving power

A measure of the clarity of an image; the ability of an optical instrument to show two objects as separate.

endomembrane system

A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles. -many different intracellular membranes form the ES, it includes nuclear envelope, ER, Golgi bodies, lysosomes, vacuoles, and plasma membrane -these are either continuous or connected through transfer by vesicles -performs tasks like: regulates synthesis/transport of proteins, regulates lipid traffic, and other metabolic functions

Match the statement with the type of microscope that it describes. Some answers may be used more than once. A. Microscope that offers the greatest magnification B. Microscope that can be used to study the surface features of cell in very high resolution C. Microscope that can be used to view live cells D. Microscope that can be used to study the organelles inside of a cell in very high resolution E. Microscope that is commonly used in biology classrooms

A. TEM B. SEM C. compound light microscope (CLM) D. TEM E. CLM

resolution

a measure of the clarity of an image -the minimum distance two points can be separated and still be distinguished as separate points

Prokaryotes are classified as belonging to two different domains. What are the domains?

Bacteria and Eukarya

Which of the following statements correctly describes a common characteristic of cell walls and the cell extracellular matrix? Both are external to the plasma membrane. Collagen is a major component of both cell walls and the extracellular matrix. Both are composed primarily of lipids. Both are synthesized in the nucleolus. Cell walls and the extracellular matrix are possessed by both plants and animals.

Both are external to the plasma membrane.

Which of the following correctly compares the extracellular matrix (ECM) of animal cells to cell walls of plant cells? Cell walls and ECMs provide for tight contact between adjacent cells. The ECM and plant cell walls completely cover the plasma membrane of their respective cells. Both the ECM and plant cell walls provide rigid structures that determine the shape of their respective cells. Both the ECM and the plant cell wall are composed of varying mixtures of proteins and carbohydrates. The structures that are external to the plasma membrane are essentially independent of the plasma membrane in both groups.

Both the ECM and the plant cell wall are composed of varying mixtures of proteins and carbohydrates.

The structure that regulates the passage of material into and out of this bacterial cell is indicated by the letter _____.

C

May store water, needed chemicals, wastes, pigments in plant cell

Central vacuole

Which of the following structures is found in animal cells but not plant cells? Centrioles Plasma membrane Rough endoplasmic reticulum Mitochondria Golgi apparatus

Centrioles

Which of the following statements about chloroplasts and mitochondria is true? Chloroplasts and mitochondria have three sets of membranes. Mitochondria but not chloroplasts contain a small amount of DNA. Chloroplasts but not mitochondria are completely independent of the cell of which they are a part. Chloroplasts and mitochondria are components of the endomembrane system. Chloroplasts and mitochondria synthesize some of their own proteins.

Chloroplasts and mitochondria synthesize some of their own proteins.

Basal bodies are most closely associated with which of the following cell components? Mitochondria Central vacuole Nucleus Cilia Golgi apparatus

Cilia

Which statement about the cytoskeleton is true? Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm. Plant cells lack a cytoskeleton because they have a rigid cell wall. Microfilaments are more permanent structures in cells than intermediate filaments and microtubules. Microtubules are chains of proteins that resist stretching. Intermediate filaments are hollow tubes of protein that provide structural support.

Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm.

can magnify specimen up to 1000X (dissecting or Compound light microscope)

Compound light microscope

Which of the following is/are possible site(s) of protein synthesis in a typical eukaryotic cell? Cytoplasm, rough endoplasmic reticulum, and mitochondria Cytoplasm and rough endoplasmic reticulum Mitochondria Cytoplasm Rough endoplasmic reticulum

Cytoplasm, rough endoplasmic reticulum, and mitochondria

The DNA-containing region of this bacterial cell is indicated by the letter _____.

D

_____ aid in the coordination of the activities of adjacent animal cells. Plasmodesmata Keratin fibers Desmosomes Tight junctions Gap (communicating) junctions

Desmosomes

A cell has formed a food vacuole as it ingested a food particle. Which of the following events is associated with the breakdown of that food particle?

Digestion of the food particle occurs in a vesicle enclosed by a membrane that separates the digestion from the cytoplasm.

What structure is shown in the image below?

Golgi apparatus

from here proteins are "shipped" to plasma membrane, outside, or other organelles

Golgi apparatus

What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell? Nucleus—ER—Golgi Golgi—ER—lysosome ER—lysosomes—vesicles that fuse with plasma membrane ER—Golgi—vesicles that fuse with plasma membrane Lysosome—ER—Golgi

ER—Golgi—vesicles that fuse with plasma membrane

In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells? Eukaryotic cells are much more successful than prokaryotic cells. Eukaryotic cells possess specialized membrane-bounded organelles. Eukaryotic cells lack many of the organelles found in prokaryotes. Eukaryotic cells can synthesize proteins, but prokaryotic cells cannot. Prokaryotic cells are larger than eukaryotic cells.

Eukaryotic cells possess specialized membrane-bounded organelles.

_____ are surface appendages that allow a bacterium to stick to a surface. Cell walls Flagella Mitochondria Ribosomes Fimbriae

Fimbriae

A researcher made an interesting observation about a protein made by the rough endoplasmic reticulum (ER) and eventually found in a cell's plasma membrane. The protein in the plasma membrane was actually slightly different from the protein made in the ER. The protein was probably altered in the . smooth endoplasmic reticulum rough endoplasmic reticulum plasma membrane transport vesicles Golgi apparatus

Golgi apparatus

revolving nosepiece

Holds and turns the objectives into viewing position

Which statement about extracellular structures (plant cell walls and the extracellular matrix of animal cells) is correct?

Information can be transmitted from these extracellular structures to the cytoplasm.

Which of the following proteins are synthesized by bound ribosomes?

Insulin, ER protein, lysosomal enzyme

eukaryotic cells

Larger, complex, with nucleus, membrane bound organelles, DNA tightly wrapped around histone proteins in chromosomes, cellulose in plant cell walls.

A researcher wants to film the movement of chromosomes during cell division. Which type of microscope should she choose, and why is it the best choice? Light microscope because of its high resolving power Transmission electron microscope because of its high resolving power Light microscope because the specimen is alive Scanning electron microscope because of its ability to visualize the surface of subcellular objects Transmission electron microscope because of its high magnifying power

Light microscope because the specimen is alive

Sac of digestive enzymes

Lysosome

Which of the following categories best describes the function of the rough endoplasmic reticulum? Energy processing Breakdown of macromolecules Structural support of cells Manufacturing Information storage

Manufacturing

Which of the following structures is found in eukaryotic but not prokaryotic cells? Ribosomes Plasma membrane DNA Cytosol Mitochondria

Mitochondria

Which structure is common to plant and animal cells? Mitochondrion Wall made of cellulose Chloroplast Centriole Central vacuole

Mitochondrion

Cilia and flagella move due to the interaction of the cytoskeleton with which of the following? Tubulin Actin Pseudopodia Motor proteins Mitochondria

Motor proteins

Which type of cell is likely to have the most mitochondria? Nondividing cells in the skin on your finger Photosynthetic cells in the leaves of a tree Muscle cells in the legs of a marathon runner Inactive yeast cells that are stored for future use Bacterial cells that are growing on sugars

Muscle cells in the legs of a marathon runner

Contains chromatin / DNA

Nucleus

main differences between eukaryotes and prokaryotes?

P: no nucleus (nucleoid region), have ribosomes (smaller and spherical), unicellular, .2-2 micrometers, complex cell wall (usually present), circular DNA, no mitochondria, cytoplasm and no organelles, plasmids, mitosis, small flagella. EX: bacteria and archaea cells E: have nucleus, have ribosomes (larger and linear), 10-100 micrometers, simple cell wall (when present), linear DNA, mitochondria, cytoplasm and organelles, rarely plasmids, binary fission, large flagella, asexual/sexual reproduction. EX: plant and animal cells

Phospholipid bilayer with proteins controls flow in and out of cell

Plasma membrane

Which of the following part(s) help adjust the amount of light reaching the specimen under observation when using the compound light microscope? Select TWO answers. Eyepieces Iris diaphragm Rheostat / dimmer switch Revolving nosepiece

Rheostat / dimmer switch Iris diaphragm

Which of the following features do prokaryotes and eukaryotes have in common? Mitochondria, cytoplasm, and plasma membrane Ribosomes, plasma membrane, and cytoplasm Mitochondria, ribosomes, and cytoplasm Nucleus, plasma membrane, and ribosomes Ribosomes, nucleus, and plasma membrane

Ribosomes, plasma membrane, and cytoplasm

Numerous ribosomes give it its name

Rough ER

prokaryotic cells

Small, simple, no nucleus, no membrane-bound organelles, single loop of DNA (nucleosome), no cellulose, cytoplasm, cell membrane, cell wall (made of carbs), sometimes have cilia or flagella (movement).

lipid synthesis, or Calcium storage or drug de-toxification

Smooth ER

Your intestine is lined with individual cells that absorb nutrients. No fluids leak between these cells from the interior of the intestine. Why? The intestinal cells are bound together by plasmodesmata. The intestinal cells are bound together by gap junctions. The intestinal cells are bound together by the extracellular matrix. The intestinal cells are bound together by tight junctions. The intestinal cells are fused together into one large cell.

The intestinal cells are bound together by tight junctions.

objective lens

The lens on a light microscope that is closest to the slide/specimen

As you increased magnification, what happened to the total number of Onion root cells remaining in your field of view?

The number of cells decreased as the field of view decreased with increased magnification.

What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane? The nuclear pores are connections between the nuclear membrane and the endoplasmic reticulum that permit ribosomes to assemble on the surface of the ER. Endoplasmic reticulum membrane is produced in the nucleolus and leaves the nucleus through the nuclear pores. Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores. The nucleolus passes through the nuclear membrane via the nuclear pores. The nucleolus contains messenger RNA (mRNA), which crosses the nuclear envelope through the nuclear pores.

Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores.

A dish of animal cells was grown in the presence of radioactive phosphorous. The phosphorous largely ended up in nucleotides inside the actively growing animal cells. In which cellular structure(s) would you predict the majority of the radioactive phosphorous to accumulate? The Golgi apparatus The Golgi apparatus and the nucleus Rough endoplasmic reticulum and Golgi apparatus Rough endoplasmic reticulum The nucleus

The Golgi apparatus

How does the magnifying power of the compound light microscope compare with that of the stereoscopic dissecting microscope?

The compound light microscope has the greater magnifying power compared to the stereoscopic dissecting light microscope

What happens to the working distance as you increase magnification?

The working distance decreases with increased magnification.

Which statements are true for chloroplasts? Select the three that apply. Their matrix contains enzymes that function in cellular respiration. Their inner membrane has infoldings called cristae. They are the sites of reactions that convert solar energy into chemical energy. They contain the green pigment chlorophyll. They have membranous sacs called thylakoids that are surrounded by a fluid called stroma. They are the sites of reactions that convert chemical energy from food molecules to ATP.

They are the sites of reactions that convert solar energy into chemical energy. They contain the green pigment chlorophyll. They have membranous sacs called thylakoids that are surrounded by a fluid called stroma.

stage platform

Used to hold slides for viewing

arm

Used to support the microscope when carried

endoplasmic reticulum function

Transport channels in the cell -transports synthesized proteins and lipids to other parts of the cell -accounts for more than half of the total membrane in eukaryotic cells -its membrane is continuous with nuclear envelope -smooth ER: lacks ribosomes rough ER: surface is studded w ribosomes

Carries secretions for export from cell

Transport vesicle

Mitochondria are found in _____.

all cells

All of the following are part of a prokaryotic cell except DNA. a cell wall a plasma membrane ribosomes an endoplasmic reticulum.

an endoplasmic reticulum.

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?

cell wall

Which of the following correctly matches an organelle with its function? central vacuole ... storage lysosome ... movement mitochondrion ... photosynthesis ribosome ... manufacture of lipids nucleus ... cellular respiration

central vacuole ... storage

Which structure is not part of the endomembrane system? All of the listed responses are part of the endomembrane system. Golgi apparatus Nuclear envelope Chloroplast Plasma membrane

chloroplast

Which structure is NOT part of the endomembrane system? Golgi apparatus plasma membrane ER chloroplast nuclear envelope

chloroplasts

iris diaphragm

controls the amount of light passing through the specimen

The primary role of _____ is to bind animal cells together. plasmodesmata gap (communicating) junctions the cytoskeleton desmosomes tight junctions

desmosomes

contrast

difference in brightness between the light and dark areas of an image

Specimen under observation may be whole and opaque.

dissecting microscope

working distance

distance between objective lens and specimen

Based on these data, what is the most likely function of the cells in this experiment? detoxification muscle contraction phagocytosis secretion

phagocytosis

what type of cells have mitochondria

eukaryotic cells, plant and animal cells

cellular functions arise from cellular order

ex: macrophage's ability to destroy bacteria involves whole cell, coordinating components such as the cytoskeleton, lysosomes, and plasma membrane

condenser

focuses light through the specimen

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through intermediate filaments. tight junctions. plasmodesmata. desmosomes. gap junctions.

gap junctions

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells? peroxisomes tight junctions extracellular matrix desmosomes gap junctions

gap junctions

transmission electron microscope (TEM)

has a resolving power of 0.0002 μm, which is 500,000 times greater than the human eye. -It is often used to visualize internal cellular structures that a light microscope cannot resolve.

Bacterial cells are prokaryotic. Unlike a typical eukaryotic cell, they . have no ribosomes lack a plasma membrane have no membrane-bounded organelles have a smaller nucleus lack chromosomes

have no membrane-bounded organelles

In a plant cell, DNA may be found in the nucleus, mitochondria, and chloroplasts. only in the nucleus and mitochondria. only in the nucleus and chloroplasts. in the nucleus, mitochondria, chloroplasts, and peroxisomes. only in the nucleus.

in the nucleus, mitochondria, and chloroplasts.

Many cell organelles, most notably the nucleus, are anchored by _____ which are assembled from a diverse class of proteins.

intermediate filaments

The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the ______.

intermediate filaments

scanning electron microscope (SEM)

is a valuable tool for studying the three-dimensional structure and surface topography of cells or small specimens

coarse adjustment and fine adjustment

knobs used for focusing specimen

ocular lens (eyepiece)

lens that is closest to the eye

The advantage of light microscopy over electron microscopy is that

light microscopy allows one to view dynamic processes in living cells.

Which organelle plays a role in intracellular digestion? Golgi apparatus lysosome chloroplast ribosome plasmodesma

lysosome

three microscope properties

magnification, resolution, contrast

The ______ is the ability to enlarge an object relative to its actual size.

magnifying power

During muscle contractions, myosin motor proteins move across tracks of _________.

microfilaments

The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of ______.

microfilaments

Which structure-function pair is MISMATCHED? Golgi; protein trafficking ribosome; protein synthesis microtubule; muscle contraction nucleolus; production of ribosomal subunits lysosome; intracellular digestion

microtubule; muscle contraction

Centrosomes are sites where protein dimers assemble into ______.

microtubules

In eukaryotic flagella, the fibers that slide past one another due to the activity of dynein proteins are

microtubules

The differences among the three categories of cytoskeletal elements outlined in the table above would suggest that each of the following has specialized roles. Which of the following is a correct match? (All three elements are involved in the maintenance of cell shape.)

microtubules and chromosome movement

endomembrane system components

nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles and the plasma membrane.

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.

plasma membrane

Dye injected into a plant cell might be able to enter an adjacent cell through . a gap junction a tight junction plasmodesmata a cell wall a microtubule

plasmodesmata

Which type of organelle is found in plant cells but not in animal cells?

plastids

What is a function of a bacterium's capsule? propulsion protection protein synthesis DNA storage

protection

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

protein

magnification

ration of an object's image size to its real size

The ________ is the ability to distinguish between two points that are very close together to one another.

resolving power

In a bacterium, where are proteins synthesized?

ribosomes

Small structure that makes protein

ribosomes

What are three structures found in all cells?

ribosomes chromosome or DNA cytoplasm cell membrane

ECM proteins are made by ribosomes in which part of a eukaryotic cell? Golgi apparatus rough ER mitochondria nuclear envelope cytoplasm

rough ER

Which structure is the site of the synthesis of proteins that may be exported from the cell? plasmodesmata lysosomes Golgi vesicles rough ER free cytoplasmic ribosomes

rough ER

You would expect a cell with an extensive Golgi apparatus to _______. move rapidly make a lot of ATP absorb nutrients in the GI tract secrete a lot of protein store large quantities of ions

secrete a lot of protein

Cell fractionation _______. separates cells into their component parts None of the listed responses is correct. requires the use of a scanning electron microscope uses strong acids to break apart cells is no longer used in modern cell biology

separates cells into their component parts

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells?

smooth ER

Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids?

smooth ER

depth of field

the distance between the nearest and the furthest objects that give an image judged to be in focus in a camera.

Which of these cell junctions form a barrier to the passage of materials? plasmodesmata tight junctions keratin fibers gap (communicating) junctions desmosomes (anchoring junctions)

tight junctions

Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____. Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____. translation of a DNA nucleotide sequence into a sequence of amino acids transferring of information from DNA to messenger RNA removal of introns from RNA and the stitching together of exons linking of nucleotides to form a polypeptide translation of an RNA nucleotide sequence into a sequence of amino acids

transferring of information from DNA to messenger RNA

When biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using a scanning electron microscope. super-resolution fluorescence microscope. phase-contrast light microscope. transmission electron microscope. confocal fluorescence microscope.

transmission electron microscope.

Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?

whether or not the cell is partitioned by internal membranes