Lecture 3 study guide

Question 1

Assume Na+ is being transported across a membrane via facilitated diffusion. What condition would allow for the most transport of Na+ across that membrane?

Answer 1

Na+ will be electrically repelled by K+ and there is a very small concentration gradient. There is very little kinetic energy driving diffusion of Na+
- a larger concentration gradient will provide greater kinetic energy to drive diffusion and Na+ will be electrically attracted to the Cl-; this will create a large electrochemical gradient

Question 2

under a microscope you view a cell with an extensive SER present. What could indicate this?

Answer 2

the cell is involved in detoxifying things

Question 3

peroxisomes —-

Answer 3

are able to detoxify substances by enzymatic action

Question 4

• Discuss how cell structure relates to function and discuss specific examples of this relationship in human cells

Answer 4

• The structure of the cell is specific to the kind of cell that it is, and is optimized for its specific function, to allow the cell to perform specific tasks.
• One example is the heart: It has 4 hollow chambers and the structure allows the heart to function and let the heart pump blood to the body.
• Bone cells: They don’t have the right structure for nerve impulse conduction.

Question 5

describe the function and composition of the plasma membrane

Answer 5

• Consists of the phospholipid bilayer (2 layers) surrounding the cell, is selectively permeable, is composed of phospholipids (a water loving head and two water fearing tails), and cholesterol (that provides structural support).

Question 6

describe the major roles of lipids in the plasma membrane

Answer 6

contribute to the shape, rigidity, and tension. Also signal, identify, traffic, maintain cellular architecture, and store energy in specific membranes.

Question 7

describe the major roles of carbohydrates in the plasma membrane

Answer 7

Cell recognition and adhesion, cell protection, make up 1-5% of chemical composition, and even cell differentiation sometimes.

Question 8

describe the major role of proteins in the plasma membrane

Answer 8

selective transport of molecules, cell to cell recognition, chemical signaling from outside and inside the cell to tell proteins where to go, acting as enzymes, providing help with the cell’s shape, and overall interaction.

Question 9

what are desmosomes

Answer 9

Are mechanical anchoring and are very strong, good for areas of the body that have a lot of mechanical stress on them. Act like a zipper to lock things in place.

Question 10

example of a desmosome

Answer 10

the heart
the muscles

Question 11

what are gap junctions

Answer 11

These are communicating junctions that leave a small gap or opening between cells so that electrical signals and ions or other things that need to move quickly from cell to cell can easily get through. These are communicating junctions that leave a small gap or opening between cells so that electrical signals and ions or other things that need to move quickly from cell to cell can easily get through. Ex: heart, anywhere else that needs quick movement.

Question 12

example of gap junctions

Answer 12

Ex: heart, anywhere else that needs quick movement.

Question 13

what are tight junctions

Answer 13

An impermeable junction in which things are not allowed through. Where you are trying to block things from passing through.e

Question 14

examples of tight junctions

Answer 14

stomach lining, bladder lining

Question 15

describe passive transport

Answer 15

passive transport does not require an input of energy (merely kinetic energy); therefore, the molecules are free to pass in and out of the cell freely
- the seesaw method

Question 16

define concentration gradient

Answer 16

• molecules tend to move down their concentration gradient
• the difference in concentration of a substance between two areas

Question 17

describe the active transport

Answer 17

• Active transport requires and input of energy (ATP), and the body powers this process by taking ATP from the body for the process. It also allows movement against its concentration gradient.

Question 18

how can substances be moved across the plasma membrane against their concentration gradient

Answer 18

• If the substance has the rights to cross like in facilitated diffusion, then specific molecules can be ferried across into the cell or out of the cell.
  
  • a substance can move freely through with a gap junction, with a tight junction it needs permission to more through.

Question 19

solute pump

Answer 19

the sodium potassium pump. When you bring in 2 Potassium for every 3 Sodium that is taken out. Is an active form of transportation and helps stabilize the resting membrane potential.

Question 20

vesicular transport

Answer 20

endocytosis -> in
- the taking in of matter by a living cell by invagination of its membrane to form a vacuole.
exocytosis -> out
- a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

Question 21

define electrochemical gradient

Answer 21

the combined differences in concentration and charge, which affects the diffusion of ions (charged particles).
- there is a electric/electro gradient and a chemical gradient. This is a combination of both

Question 22

explain how the electrochemical gradient influences the movement of substances across the plasma membrane

Answer 22

• Allows the cells to control individually how and in what direction ions move across the membranes in and out of the cells

Question 23

electrical vs. chemical gradient

Answer 23

electrical - the difference in charge across the membrane
chemical - the difference in solute concentration across the membrane

Question 24

define membrane potential

Answer 24

the measurement of the difference in charge across the membrane

Question 25

describe the function and composition of the cytoplasm

Answer 25

the intracellular components found between the plasma membrane and the nucleus.
cytosol - viscous, semitransparent fluid substance of cytoplasm in which other elements are suspended.
inclusions - chemical substances that may or may not be present, depending on the cell type
cytoplasmic membrane - a fluid phospholipid bilayer that separates and protects the interior of a cell from the outside environment

Question 26

what do pigment cells do

Answer 26

the number of pigment cells in our bodies cells decide the pigment color of our skin

Question 27

mitochondria

Answer 27

site of ATP synthesis; powerhouse of the cell. Rodlike, double-membrane structures; inner membrane folded into projections called cristae.

Question 28

ribosomes

Answer 28

the sites of protein synthesis, dense particles consisting of two subunits, each composed of ribosomal RNA and protein. Free or attached to RER.

Question 29

rough endoplasmic reticulum

Answer 29

membranous system enclosing a cavity, the cistern and coiling through the cytoplasm. Externally studded with ribosomes. Sugar groups are attached to proteins within the cisterns. Proteins are bound in vesicles for transport to the Golgi Apparatus and other sites. External face synthesis phospholipids.
- is associated with many roles in protein synthesis, which also include post-translational modifications, folding, and sorting

Question 30

smooth endoplasmic reticulum

Answer 30

membranous system of sacs and tubules; free of ribosomes. Site of lipid and steroid (cholesterol) synthesis, lipid synthesis, lipid metabolism, drug detoxification, and Ca2+ storage.

Question 31

golgi apparatus

Answer 31

a stack of flattened membranes and associate vesicle close to the nucleus. Packages, modifies, and segregates proteins for secretion from the cell, inclusion in lysosomes, and incorporation into the plasma membrane. Modifies carbohydrates on proteins.

Question 32

peroxisomes

Answer 32

Membranous sacs containing catalase and oxidase enzymes. The enzymes detoxify a number of toxic substances. The most important enzyme, catalase, breaks down hydrogen peroxide.

Question 33

lysosomes

Answer 33

membranous sacs containing acid hydrolases. Sites of intracellular digestion

Question 34

centrioles

Answer 34

Paired cylindrical bodies, each composed of nine triplets of microtubules. They organize the microtubule network

Question 35

the three important cytoskeletal elements

Answer 35

microfilaments
intermediate filaments
microtubules

Question 36

microfilaments

Answer 36

fine filaments composed of the protein actin. Involved in muscle contraction and other types of intracellular movement; help from the sell’s cytoskeleton.

Question 37

intermediate filaments

Answer 37

protein fibers; composition varies. The stable cytoskeleton elements; resist mechanical forces acting on the cell.

Question 38

microtubules

Answer 38

cylindrical structures made of tubulin proteins, support the cell and give it shape. Involved in intracellular and cellular movements. Form centrioles and cilia and flagella, if present.

Question 39

describe the composition of chromatin

Answer 39

• Is a dense spherical (non-membrane-bounded) bodies, composed of ribosomal RNA and proteins. Is the site of ribosome subunit manufacture.

Question 40

describe multinucleate and anucleate

Answer 40

• Multinucleate – having more than one nucleus
• Anucleate – lacking a cell nucleus

Question 41

describe the structure and function of the nucleus

Answer 41

The nucleus is a spherical or oval organelle in a cell that contains the cell’s DNA and controls cell activities.
- the nucleus is like the brain of all of the cells

Question 42

nuclear envelope

Answer 42

double membrane structure pierced by pores. Outer membrane continuous with the endoplasmic reticulum.
- separates the nucleoplasm from the cytoplasm and regulated passage of substances to and from the nucleus (separates the chromatin and nucleolus from the cytoplasm. Is a wall between the chromatin/nucleolus and the nucleus

Question 43

nucleolus

Answer 43

dense spherical (non-membrane-bound) bodies, composed of ribosomal RNA and proteins. Site of ribosomes subunit manufacture

Question 44

chromatin

Answer 44

granular, threadlike material composed of DNA and histone proteins, DNA constitutes the genes

Question 45

nucleus

Answer 45

• largest organelle, surrounded by the nuclear envelope; contains fluid nucleoplasm, nucleoli, chromatin.
• control center of the cell; responsible for transmitting genetic information and providing the instructions for protein synthesis

Question 46

Cilia

Answer 46

Is involved in propelling substances across the cell surface

Question 47

Simple diffusion is best described as?

Answer 47

Moving passively down the concentration gradient

Question 48

The Golgi apparatus produces what

Answer 48

Secretory vesicles

Question 49

a gap junction is what kind of transport?

Answer 49

passive transport