Bio Test 3 Ch. 4 Flashcards

Ch. 4 Terms

cell theory

The theory that all living things are composed of cells and that all cells come from other cells

cell wall

-Present in prokaryotes and plants
-Rigid, helps protect shape and maintain structure
-Plant cell wall is different than prokaryotes (contains the polysaccharide cellulose)

cellular metabolism

The chemical activities of cells

central vacuole

-specific to PLANTS
-large membranous sac with roles in growth and safe storage of vital chemicals, toxic wastes
-helps cell grow in size by absorbing water, enlarging

centrosome

-Specific to ANIMALS
-Structure containing two centrioles (made of microtubules), from which microtubules are produced

chloroplast

-Organelle found in plants and algae
-Photosynthesizes, converts light energy to chemical energy
-Thylakoids within chloroplast contain chlorophyll, which traps solar energy and provides green color
-Evolved from photosynthetic bacteria (endosymbiosis)

chromatin

Complex of DNA and proteins that make up eukaryotic chromosomes, contained in nucleus

chromosome

Threadlike structure of nucleic acids and protein, carrying genetic information in the form of genes

cilium (plural, cilia)

Short, hair-like organelle that helps some cells swim (e.g. paramecium cells)

-cilia on cells lining trachea help push debris, mucus out of lungs

cytoplasm

Inside of the cell, in which organelles are suspended (refers to semi-fluid medium and organelles)

cytoskeleton

Network of protein fibers in the cell (includes microfilaments, intermediate filaments, and microtubules)
-interaction with motor proteins contributes to mobility of cell parts

cytosol

Fluid portion of cytoplasm

electron microscope

-Forms image by focusing beams of electrons through specimen or onto its surface
-Better magnification than light microscopes
-No true color, can't be used to see living cells because electrons destroy samples

endomembrane system

A network of membranes inside and surrounding eukaryotic cell, some linked through physical contact and some linked when membranous sacs called vesicles transfer membrane segments between them

smooth endoplasmic reticulum

Synthesizes LIPIDS, regulates calcium levels, and breaks down toxic substances

-Sex cells have high levels of smooth ER to produce necessary amount of steroids/hormones
-Liver cells have large amount of smooth ER to process alcohol, drugs, and other harmful materials
-When signaled, calcium ions rush from smooth ER to cytosol to trigger contraction of muscle cell

rough ER/protein synthesis

The Rough ER has ribosomes attached to its membrane, which start the process of protein synthesis:
1. Attached ribosome follows mRNA instructions to create polypeptide
2. Polypeptide is threaded into ER membrane, sometimes sugar chains are attached to create a glycoprotein
3. When ready for export from the rough ER, it's packaged in transport vesicle and buds off from ER membrane

endosymbiont theory

The theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell, which then evolved into a single organism. The mitochondria evolved from aerobic bacteria and the chloroplasts evolved from photosynthetic bacteria. Evidence includes: both mitochondria and chloroplasts undergo binary fission like prokaryotes, both have their own ribosomes and circular DNA, etc.)

eukaryotic cell

A cell with a nucleus and membrane-enclosed organelles
-often larger than prokaryotic cells, contains bigger ribosomes

extracellular matrix (ECM)

meshwork surrounding animal cells, consisting of glycoproteins and polysaccharides synthesized and secreted by cells

flagellum (plural, flagella)

-Long, whiplike structure that propels a cell
-Consists of microtubules (9 microtubule doublets surrounding central pair of microtubules) surrounded by extension of the plasma membrane

glycoprotein

A protein with one or more carbohydrates (e.g. sugar chains) covalently attached to it.

Golgi apparatus

Organelle in cells consisting of stacks of membranous sacs that modify, sort, and package products of the endoplasmic reticulum for export or use in the cell
1. One side of Golgi stack serves as receiving dock for transport vesicles produced by ER
2. Vesicle fuses with Golgi sac, adds membrane and contents to receiving side
3. Products of ER are modified as they move through the stack
4. "Shipping side" of Golgi releases products in vesicles that bud off and travel to other sites

intermediate filament

-More permanent part of the cytoskeleton, found in most animal cells
-Made of various fibrous proteins that coil into cables, reinforcing cell shape and anchoring organelles
-Nucleus sits in cage of intermediate filaments

light microscope

-Lenses refract visible light to magnify images of specimens
-Max magnification around 1000x
-Can see true color, living specimens

lysosome

-Like centrosomes, these are mainly specific to ANIMALS
-Organelle containing membrane-enclosed digestive enzymes
-lysosome parts made in rough ER, processed in Golgi
-FUNCTIONS:
-can fuse with food vacuoles to break down food, release nutrients into the cytosol
-white blood cells engulf bacteria, destroy w/ lysosomes
-needed for cellular renewal - can fuse with old cell parts within vesicle, break them down/recycle them

microfilament

Solid rod of proteins called actin, thinner than microtubule but vital to maintaining shape of cells (especially animal cells, which lack a cell wall)

microtubule

Straight, hollow tubes made of globular proteins called tubulins, found in cilia, flagella, and the cytoskeleton of all eukaryotic cells

mitochondrial matrix

Compartment of the mitochondrion, enclosed by the inner membrane, contains mitochondrial DNA, ribosomes, and enzymes that catalyze some of the reactions of cellular respiration

mitochondrion (plural, mitochondria)

-Energy-processing organelle in eukaryotic cells that undergoes cellular respiration, produces ATP to power cell
-Uses oxygen -> converts food's chemical to ATP -> releases carbon dioxide

motor protein

-Protein that interacts with cytoskeletal elements
-Produces movement of whole cells or parts of cell

nuclear envelope

Double membrane surrounding nucleus of eukaryotic cell, perforated with protein-lined pores that regulate traffic of large molecules, connect with ER

nucleoid

A dense region of DNA in a prokaryotic cell (nucleus-like, but not membrane-enclosed)

nucleus

Control center of the cell, contains genetic material in the form of chromosomes made of chromatin

nucleolus

Found inside the nucleus; produces ribosomes

organelle

A tiny cell structure that carries out a specific function within the cell

peroxisome

Small vesicles containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea

ribosome

-Use instructions from mRNA to synthesize proteins- translate nucleotide sequence into polypeptide chain
-Cells that make a lot of proteins have larger # of ribosomes (e.g. pancreatic cell with digestive enzymes may contain a few million ribosomes)
-subunits of ribosomes are assembled in the nucleolus
-Free ribosomes suspended in cytosol, attached ribosomes found on outside of rough ER

transport vesicle

Tiny membranous sacs that carry molecules from one cell part to another

vacuole

-Cell organelle that stores materials such as water, salts, proteins, and carbs
-Can protect plant by storing compounds that are harmful to herbivores (making it poisonous to eat)
- Vacuoles in flower petals store pigments that attract pollinators

vesicle

A membrane bound sac that contains materials involved in transport of the cell