Biology Review Questions for Exam 2

What are phospholipids? How does their structure affect their role?

They are made up of a phosphate head and a lipid tail. In between them is a long chain of hydrogen and carbon. The length, kinks, and cholesterol in it help make it have more fluidity in the membrane.

What are the differences between an antiporter, a symporter, and a uniporter?

Uniport- Integral protein which moves one type of molecule across the membrane Symport- Integral protein which moves two or more molecule types across the membrane in the same direction. Antiport- Integral protein which moves two or more molecule types across the membrane in the opposite direction.

What is the difference between integral and peripheral membrane proteins?

integral proteins are embedded(bound) in the whole bilayer whereas peripheral proteins are located on the inner or outer surface of the phospholipid bilayer.

What is glycosylation? What does glycosylation produce?

is the process of adding a carbohydrate to a lipid or protein (forming glycolipids or glycoproteins, respectively)

How do transmembrane proteins become embedded in the plasma membrane?

the transmembrane proteins are often transmembrane receptors, and will usually pass through a membrane several times. They are anchored into the membrane by translocation and then will be stopped by a membrane anchor sequence which will allow them to stay embedded.

What happens to plant/animal cells when placed in either a hypotonic, hypertonic, or isotonic solution?

- isotonic : it is ideal for animal cells, while for plant cells it is not. The plant cell will go flaccid/wilt. - Hypertonic : Plants become plasmolyzed and animal cells will experience crenation. - For hypotonic : plant cells gain water and it is said to be turgid. Animal cells undergo lysis.

Describe the stages of cell signaling.

1. Reception 2. Transduction 3. Response

What is the difference between active and passive transport?

Active transport requires energy (ATP), while passive transport does not (Diffusion, Osmosis).

What is the difference between exocytosis and endocytosis?

Exocytosis : Material inside the cell is packaged and shipped outside of the cell. Endocytosis : Material on the outside of the cell is packaged and shipped in vesicles to the interior of the cell.

Describe 3 ways a cell can communicate with cells immediately around it.

Gap junctions, tight junctions, and desmosomes.

What is the difference between osmosis and diffusion?

Osmosis is the movement of water across the membrane while diffusion is the movement of solutes.

How can you tell whether a solution is hypertonic, hypotonic, or isotonic to a cell placed within it?

A solution is isotonic when it has the same amount of solutes. A solution is hypertonic when it has a lot solute. A solution is hypotonic when it has little solute.

Describe how a cell communicates with cells very far removed from it.

By endocrine signaling. Lipids called hormones are secreted by the cell, travelling via the circulatory system to far distant areas of the organism.

What are 6 functions of the cell membrane?

Cell compartmentalization, anchoring cytoskeleton, protein sorting, adhesion of cells, cell signaling, selective uptake and export of ions and molecules.

What is the difference between a channel protein and a transport protein?

Channel protein : Transmembrane proteins that have an open structure in the center that allow molecules to move back and forth through the cell membrane Transport protein : transport ions and molecules either passively through facilitated diffusion, or via secondary active transport.

What 3 types of macromolecules compose the plasma membrane?

Lipids, Proteins, and Carbohydrates

What does it mean to be semi-permeable?

Small molecules can pass through easily like water, but large molecules have a difficult time.

Why is the phospholipid bilayer termed a semifluid?

Some proteins can float through the membrane while some proteins are anchored into the membrane.

What is selective permeability?

The cell membrane forms a barrier that lets some molecules enter and exit the cell, while preventing others from doing so.