a & p ch 3 : cells

what is cell theory (3 things)

cell is smallest unit of life

all organisms are made of one or more cells

cells arise only from other cells

how many different types of cells are there

over 250

are phosphate heads hydrophobic or hydrophilic

hydrophilic

are phosphate tails hydrophobic or hydrophilic

hydrophobic

what allows for cells to adhere and communicate to other cells

• tight junctions

• desmosomes

• gap junctions

what is a tight junction

proteins on adjacent cells fuse to form a tight, waterproof junction that encircles the whole cell and allows for connection.

prevents fluids and molecules from moving between cells

what is a desmosome

rivet-like junctions formed with linker proteins lock with other desmosomes; have an appearance of a zipper

helps keep cells from tearing apart

what is a gap junction

transmembrane proteins form tunnels that allow molecules to pass between cells

allows signals to be shared quickly from one cell to another

what is passive transport?

no energy required for transport across the membrane

what is active transport?

ATP is needed for transport across the membrane

what is diffusion

molecule movement from high to low concentration

what are 3 things that can speed up diffusion?

the concentration between two areas

molecule size (bigger is slower, smaller is faster)

temperature; higher temps increase energy which makes diffusion faster

when does a system reach equilibrium

when there is no net movement of molecules in one direction

what is facilitated diffusion

water soluble and large molecules needing help crossing the membrane

what is simple diffusion

lipid soluble molecules and small molecules can cross the membrane with no help

what are 2 ways molecules can be passed through the membrane in facilitated diffusion

through carriers; substances binding to protein carriers

channel diffusion; substances move through water filled channels

what does the sodium-potassium pump do?

moves 3 NA+ out of the cell and 2 K+ into the cell against (up) the concentration gradient

ATP is used to move the substances in and out of the cell

affinity (shape) of the protein changes to fit thee NA or the K in the carrier

what is osmolarity

total concentration of all solute particles

what is tonicity

ability of a solution to change the shape of cells by altering their internal water volume

what is an isotonic solution

same concentration of solute and solvent in and out the cell. equal.

what is a hyportonic solution

higher concentration inside the cell, causing it to grow and potentially lyse.

water flows into the cell causing it to grow.

what is a hypertonic solution

higher concentration outside the cell, causing water to be pulled out of the cell and shrink (crenation)

what is a symporter

transport molecules the same direction

what is an antiporter

transports molecules in opposite direction

what is vesicular transport

moves large substances or large amount of substances across the membrane in vesicles (membrane sacs)

what do lysosomes do

contain digestive enzymes

digest bacterias, viruses and toxins

what do peroxisomes do

neutralize toxins,

what are the mitosis phases

prophase

metaphase

anaphase

telophase

what is cytokinesis

division of the cytoplasm, after telophase

what is phase g1

growth phase; restriction point

what is S phase

growth and DNA synthesis

what is g2 phase

growth and final prep for division; M checkpoint

what are the 3 phases of transcription

initiation

elongation

termination

what is initiation phase

RNA polymerase separates DNA strands

what is elongation phase

RNA polymerase creates DNA strands based off of different codons

what is termination phase

when RNA polymerase hits a STOP codon, it stops transcription

what is translation ?

protein synthesis where language of nucleic acid base codon is translated into protein (amino acid) sequences