college biology-chapter 4

nuclear envelope

phospholipid bilayer, innermost surface has DNA attachment sites, pores span bilayer

nucleolus

one or more masses of dense material in the nucleus, ribosomes made

chromatin

loose DNA when cell is not actively dividing

Endoplasmic Reticulum

(in animal cells) continuous with nuclear membrane, extends throughout cytoplasm (rough+smooth)

smooth ER

interconnected tubules without ribosomes on the surface / lipid assembly, inactivates waste and drug (such as in the liver)

golgi bodies

put finishing touches on proteins and lipids arriving from the ER / package finished material

vesicles

membranous sacs that can pass through cytoplasm (lysosome+peroxisome)

lysosome

vesicle with digestive enzymes / breakdown cell parts

peroxisome

vesicle that breaks down fatty acids and amino acids / hydrogen peroxide (H2O2)

thylakoid

flattened discs in chloroplasts / photosynthesis+chlorophyll / light reactions in membrane

granum

stack of thylakoids

stroma

dark reaction center

chromoplast

(plastid) store red and brown pigments

amyloplast

(plastid) lack pigments, store starch

endosymbiosis theory

mitochondria and chloroplasts were independent prokaryotic cells that were engulfed by another cell (own DNA, RNA, ribosomes)

Plasmodesmata

channels between plant cells for communication and nutrient exchange

tight junction

type of cellular junction between animal cells that prevents leakage / very tightly packed

adhering junction

cell junction in animal cells... stretchy/present in heart tissue, skin, lungs

gap junctions

the plasmodesmata of animal cells / channels for communication and nutrient exchange

cytoskeleton

present in all eukaryotic cells / basis for cell shape and internal organization / allows movement

microtubule

largest element of the cytoskeleton / composed of protein tubulin / move chromosomes during cell division / involved in shape

microfilament

thinnest element of the cytoskeleton / composed of protein actin / take part in movement, formation, and maintenance of cell shape / cell cortex

intermediate filaments

present in certain animal tissues / most stable of the cytoskeleton / strengthen and maintain cell shape

motor proteins

attach to microtubules and microfilaments (kinesin, dynein, myosin)

centrioles

barrel-shaped structures found near the nucleus / made of microtubules / used during cell division in ANIMAL CELLS, organize microtubles in cilia or flagella

pseudopods

"false feet" (ex: amoeba) / function in locomotion and prey capture

Robert Hooke

coined the term "cell"

Robert Brown

discovered the nucleus

characteristics of life

must have cells, be able to reproduce, react to stimuli, energy, grow, evolve, maintain homeostasis, have DNA

cell

smallest unit with the properties of life

nucleus

membrane-bound organelle that contains a cell's DNA / control center of the cell

cytoplasm

everything between the plasma membrane and the region of DNA

ribosomes

molecular structures on which protein is built

prokaryotic

No nucleus (archae and eubacteria)

eukaryotic

Has a nucleus (plants, animals, protists, fungi)

chromosome

long, tight strand of DNA

rough ER

flattened sacs with ribosomes on the surface / polypeptide chains enter and are modified

mitochondria

ATP-producing powerhouse, double-membrane system / carry out most efficient energy-releasing reactions, reactions require oxygen

cristae

folds in the inner membrane of mitochondria

chloroplast

(plastid) convert sunlight energy to ATP through photosynthesis

central vacuole

stores water, amino acids, sugars, waste / 50-90% of mature plant cell interior

cell wall

structural component that wraps around the plasma membrane / occurs in plants, fungi, and some protists