ap bio unit 2 (ch 4 and 5)

cell theory

all living things are composed of cells, cells are the basic units of structure and function in living things, new cells are produced from existing cells

prokaryotic cells

simple, lack a nucleus, and membrane-bound organelles ex.) bacteria

eukaryotic cells

complex, contain a nucleus, and membrane organelles ex.) plants, animals, fungi, protists

nucleus

contains DNA, control center of the cell

ribosomes

sites of protein synthesis; can be free in the cytoplasm or bound to the endoplasmic reticulum

rough endoplasmic reticulum

studded with ribosomes; synthesizes proteins

smooth endoplasmic reticulum

lacks ribosomes; synthesizes lipids and detoxifies substances

golgi apparatus

Modifies, sorts, and packages proteins and lipids for storage or transport out of the cell

mitochondria

powerhouse of the cell; site of ATP (energy) production through cellular respiration

chloroplasts

site of photosynthesis in plant cells

lysosomes

contain digestive enzymes to break down waste materials and cellular debris

vacuoles

storage sacs; larger in plant cells, storing water, nutrients and waste

cytoskeleton

provides structural support and facilitates movement within the cell

mitosis (cell division)

cell replication

meiosis (cell division)

formation of gametes

transcription (protein synthesis)

Transcription is the process by which DNA is copied (transcribed) to mRNA, which carries the information needed for protein synthesis. DNA - TCAG will be transcribed to AGUC

translation (protein synthesis)

reading the mRNA codons to make proteins; occurs on the ribosomes

structure of cell membranes

composed of a phospholipid bilayer with embedded proteins

fluid mosaic model

membrane is flexible with proteins that move within the lipid bilayer

intergral proteins

span the membrane; involved in transport and signaling

peripheral proteins

loosely attached to the membrane; play roles in signaling and maintaining the cell's shape

passive transport

movement of molecules across the membrane without energy ex.) diffusion, facilitated diffusion, osmosis

active transport

movement of molecules against their concentration gradient, requiring energy ex.) sodium-potassium pump

signal transduction pathways

a series of steps by which a signal on a cell's surface is converted into a specific cellular response

receptors

proteins that bind to signaling molecules (ligands) and initiate a response

G-Protein Coupled Receptors (GPCRs)

activated a G-protein that relays signals

Receptor Tyrosine Kinases (RTKs)

enzyme-linked receptors that phosphorylate tyrosine residues on themselves and other proteins

second messengers

small molecules ex.) cAMP, calcium ions that relay signals within the cell

direct contact

cells communicating through gap junctions or plasmodesmata

local signaling

use of paracrine signaling (cells communicating over short distances) and synaptic signaling in neurons

long-distance signaling

endocrine signaling via hormones

surface area to volume ratio

as an object increases in volume, its surface area also increases, but not as quickly

selective permeability

A property of a plasma membrane that allows some substances to cross more easily than others.

simple diffusion

movement of a solute from an area of high concentration to an area of low concentration

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels

surface area of a cell

determines the amount of substances that can enter from the outside environment, and the amount of waste products that can exit to the environment

volume of a cell

determines the amount of metabolic activity it carries out per unit of time