the cell structure and function

functions of the cell

metabolism, synthesis, communication, reproduction and inheritance

basic composition

cell membrane, cytoplasm, organelles, nucleus

cell membrane

plasma membrane consists of phospholipid bilayer with proteins and cholesterol molecules dispersed within

separates intracellular and extra cellular materials

membrane potential

production of charge difference across membrane by regulation of intracellular and extra cellular ion concentrations

fluid mosaic model

phospholipid units reassemble if membrane is damaged

integral proteins

act as channel

peripheral proteins

attached to only one side of membrane

attachment proteins

attach cells to other cells or molecules

channel proteins

non gated ion channels, always integral and open

gated, voltage or ligand depending, sometimes closed always integral

carrier proteins

transporters

have specific binding sites and change shape to transport ions/molecules

receptor proteins

attach to specific chemical signal molecules and act as intercellular communication system

ligands can only attach to cells with specific receptors

lock and key

passive transport

movement doesnt require energy

2 forms:

simple diffusion, higher to lower concentration

facilitated diffusion, higher to lower with help from membrane proteins

active transport

movement requires energy (atp)

lower to higher concentration

rate depends on atp

osmosis

diffusion of water, lower solute to higher solute concentration

hypotonic solution

less solute on outside of cell membrane, water enter cells (cell swells-lysis)

hypertonic solution

more solute on outside of cell membrane, cell shrinks (crenation)

isotonic solution

equally distributed solute on either side of cell membrane

optimal for cell function

filtration

depends on pressure difference on either side of a membrane

moves from side of greater pressure

endocytosis

internalization of substances by formation of a vesicle

2 types

phagocytosis - cell eating

pinocytosis - cell drinking

exocytosis

substances being expelled

cytoplasm

cell filler outside nucleus but inside plasma membrane

composed of cytoskeleton (microtubules/microfilaments) and cytosol (fluid portion)

essential

mostly water

endoplasmic reticulum

system of membranes that make up cisternae

rough er and smooth er

rough er

facilitates protein synthesis

ribosomes made of rna

made from outer shell nucleus

smooth er

manufactures and transports fats and lipids

calcium storage

detox

sex hormone synthesis

ribosomes

rna containing bodies

prod in nucleolus

protein synthesis

golgi apparatus

flattened membrane sacs stacked on each other

function- modification, packaging, sorting out, and preparing proteins and lipids for distribution (secretion or internal)

post office

mitochondria

powerhouse of cell

cristae: inner folds where cellular respiration occurs

higher need for atp, more mitochondria

lysosomes

tiny sacs filled with digestive enzymes

digest stored nutrients

help break down dysfunctional structures (waste/byproducts)

centrioles

located in centrosome (specialized zone near nucleus)

center of microtubule info

forms spindle fibers during cell division

guide duplicated chromosomes to form identical daughter cells-must split evenly

microvilli

cell membrane projection

multiple extensions of plasma membrane which do not move

increase surface area

cilia

cell membrane projection

fine hair like capable of movement extensions from cell membrane

multiple per cell

move materials across cell surface

like moving belt

flagella

cell membrane projection

similar to cilia but longer and single

propel the whole cell in wave like fashion (tail)

nucleus

organelle

control center of cell w dna

membrane has pores to allow passage of substances

chromatin

genetic material inside nucleoplasm is finely dispersed during state of rest

chromosomes

during cell division, chromatin condenses and forms tiny structures

same material assembled differently

nucleolus

site of ribosome formation

transcription

dna info being copied

mrna formed

translation

mrna directs new protein synthesis

converting copied info into protein

gene

functional unit of heredity

each gene occupies a specific place within chromosomes- locus

structural, template for mrna, code for amino acid sequences

regulatory, control which structural genes transcribed in given tissue

genotype

actual set of alleles a person has for a given trait

phenotype

persons appearance

allele

different forma of same gene

homozygous

2 of same allele for a trait

heterozygous

one dominant one recessive

karyotype

map of chromosomes

genetic disorders

abnormalities in dna

congenital disorders

birth defects not necessarily genetic

teratogens, agents that cause birth defects

mutation

mutagens, agents that cause mutations

cancer

tumor resulting from uncontrolled cell division

oncogenes, genes associated with cancer, tumor supression

interphase

in between 2 divisions

mitosis, prophase

nuclear envelope disintegrates, chromatin condenses, formation of chromosomes

mitosis, metaphase

chromosomes are aligned at the nuclear equator

mitosis, anaphase

chromatids separate and form chromosomes (2 identical sets)

mitosis, telophase

chromosomes decondense, nuclear envelope reforms, cytokinesis continues

cytokinesis

division/separtion of the cytoplsm, formation of two separate but identical daughter cells, separate process from mitosis