BIO 201 Exam Cells and Molecular Biology With complete verified solutions + Rationales

cell theory

The cell is the basic structural and functional unit of life; 1. Organismal activity depends on individual and collective activity of cells

2. Biochemical activities of cells are dictated by subcellular structure

3. Continuity of life has a cellular basis

cell size

cell growth increases volume more than surface area; surface area of a cell is proportional to the square of its diameter; volume of a cell is proportional to the cube of its diameter; volume increases faster than surface area

plasma membrane

surrounds cell, made of proteins and lipids, composition and function can vary from one region to another

mechanical barriers

Separates two of the body's fluid compartments

selective permeability

Determines manner in which substances enter or exit the cell

electrochemical gradients

Generates and helps to maintain the electrochemical gradient required for muscle and neuron function

communications

Allows cell-to-cell recognition (e.g., of egg by sperm) and interaction.

cell signaling

Plasma membrane proteins interact with specific chemical messengers and relay messages to the cell interior.

receptor

always have a very specialized little area called the binding site; only specific shape that messengers will bind to; they are how cells communicate from outside of themselves; messenger causes receptor to change shape

enzyme

breaks down a chemical messenger and terminates its effect

ion channel

this is constantly allowing ions to flow from one side of the membrane to the other; leakage ion channel, always open

gated ion channel

A gated channel that opens and closes to allow ions through only at certain times

cell identity marker

A glycoprotein acting as a cell- identity marker distinguishing the body's own cells from foreign cells

cell adhesion molecule

A cell-adhesion molecule (CAM) that binds one cell to another

g-protein

can affect ion channels, activate other enzymes, or cause release of internal second messenger chemicals such as cyclic AMP or calcium

microvilli

Minute, fingerlike extensions of plasma membrane that project from surface of select cells (example: intestinal and kidney tubule cells); Used to increase surface area for absorption; DO NOT MOVE

cilia

whiplike, motile extensions on surfaces of certain cells (such as respiratory cells); work together in sweeping motion to move substances (example: mucus) across cell surfaces in one direction

flagella

longer extensions that propel the whole cell (example: tail of sperm)

tight junction

Prevent fluids and most molecules from moving in between cells; forces fluid though cells; "zipper like"

desmosomes

Rivet-like cell junction formed when linker proteins (cadherins) of neighboring cells interlock like the teeth of a zipper; Linker protein is anchored to its cell through thickened "button-like" areas on inside of plasma membrane called plaques

gap junctions

Transmembrane proteins (connexons) form tunnels

that allow small molecules to pass from cell to cell; Used to spread ions, simple sugars, or other small molecules between cells

active transport

consumes ATP

passive transport

requires no ATP

simple diffusion

fat-soluble molecules directly passing through the phospholipid bilayer

directly pass through plasma membrane

Non polar, hydrophobic, lipid-solublesubstances

facilitated diffusion

Certain hydrophobic molecules (e.g., glucose, amino acids, and ions) are transported passively down their concentration gradient

Carrier-mediated facilitated diffusion

Substances bind to protein carriers

Channel-mediated facilitated diffusion

Substances move through water-filled channels

specificity

certain receptor can only binds certain things; ex sugar receptor only bind sugar

factors that affect diffusion rate

1) temperature- temp., motion of particles

2) molecular weight - larger molecules move slower

3) steepnessofconcentratedgradient- difference, rate

4) membranesurfacearea- area, rate

5) membranepermeability- permeability, rate

osmosis

Movement of solvent, such as water, across a

selectively permeable membrane

aquaporins

water channels in the membrane

hydrostatic pressure

pressure of water inside cell pushing on membrane

osmotic pressure

endency of water to move into cell by osmosis

reverse osmosis

Water & solutes can leak out of capillary in between cells

tonicity

Ability of a solution to change the shape or tone of

cells by altering the cells' internal water volume

isotonic solution

has same osmolarity as inside the cell, so volume remains unchanged

hypertonic solution

has higher osmolarity than inside cell, so water flows out of cell, resulting in cell shrinking; crenation

hypotonic solution

has lower osmolarity than inside cell, so water flows into cell, resulting in cell swelling; lysing

pinocytosis

"the cell drinking"

small particles and something that is unspecified; general particle being brought into cell

phagocytosis

Consumption of a large object- such as a bacterium- by another cell

exocytosis

secreting material out of the cell; replacement of plasma membrane removed by endocytosis

Transcytosis

Transport of material across the cell by capturing it on one side and releasing it (more or less unchanged) on the other; like how insulin is taken into cells

cytoplasm

All cellular material that is located between the plasma membrane and the nucleus; composed of cytosol, inclusions, and organelles

inclusions

nsoluble molecules; vary with cell type (examples: glycogen granules, pigments, lipid droplets, vacuoles, crystals); packages of stuff that accidentally got into the cell

cytosol

gel-like solution made up of water and soluble molecules such as proteins, salts, sugars, etc.

mitochondria

Called the "power plant" of cells because they produce most of cell's energy molecules (ATP) via aerobic (oxygen-requiring) cellular respiration; contain their own DNA, RNA, and ribosomes

nucleus

Largest organelle; contains the genetic library of blueprints for synthesis of nearly all cellular proteins

nuclear envelope

Double-membrane barrier that encloses the jelly-like fluid, the nucleoplasm

nucleoli

Dark-staining spherical bodies within nucleus that are involved in ribosomal RNA (rRNA) synthesis and ribosome subunit assembly

chromatin

Consists of 30% threadlike strands of DNA, 60% histone proteins, and 10% RNA

chromosomes

condensed chromatin

cytoskeleton

act as cell's "bones, ligaments, and muscle" by playing a role in movement of cell components

microfilaments

Thinnest of all cytoskeletal elements; Semi-flexible strands of protein actin*; Some are involved in cell motility, changes in cell shape, or endocytosis and exocytosis

intermediate filaments

Tough, insoluble, ropelike protein fibers; part of cytoskeleton; Help cell resist pulling forces; help restist compression

microtubules

Largest of cytoskeletal elements; consist of hollow

tubes composed of protein subunits called tubulins, which are constantly being assembled and disassembled; Determine overall shape of cell and distribution of organelles

centrosome

It is a microtubule organizing center, consisting of a granular matrix and centrioles—a pair of barrel-shaped microtubular organelles that lie at right angles to each other

endomembrane system

Consists of membranous organelles discussed so far (ER, Golgi apparatus, secretory vesicles, and lysosomes), as well as the nuclear and plasma membranes

lysosomes

made by the golgi apparatus; Digest ingested bacteria, viruses, and toxins

peroxisomes

Membranous sacs containing powerful detoxifying substances that neutralize toxins

golgi apparatus

Modifies, concentrates, and packages proteins and lipids received from rough ER

smooth ER

― Lipid metabolism; cholesterol and steroid-based hormone synthesis; making lipids for lipoproteins

― Absorption, synthesis, and transport of fats

― Detoxification of certain chemicals (drugs,

pesticides, etc.)

― Converting of glycogen to free glucose

― Storage and release of calcium

Sarcoplasmic reticulum is specialized smooth ER found in skeletal and cardiac muscle cells

rough ER

External surface appears rough because it is studded

with attached ribosomes

― Site of synthesis of proteins that will be secreted from cell

― Site of synthesis of many plasma membrane proteins and phospholipids

ribosomes

Nonmembranous organelles that are site of protein synthesis