Biology--Cell Structure (Year 1, Unit 1)

theory

a well-substaintiated explanation of an aspect of the natural world that can incorporate laws, hypotheses, and facts

Cell theory

cells are the fundamental units of living organisms

cells are the smallest unit of life

new cells arise from pre-existing ones

Magnification equation:

Image size = actual size x magnification

electron microscope

black and white

specimens not living

electrons have a short wavelength, and can create more focused images at higher magnifications

max 1,000,000 magnification

light microscopes

allows observation of living organisms in color

living speciments

max 2,000x magnification

methylene blue

binds to nucleic acids (nucleus is dark blue)

iodine

binds to starches (can see cell walls and starch grains)

flourescent stains

absorb light at one wavelength and emit light at another one: Flourescnet molecule is attached to an antibody, which binds to a target protein

freeze fracture

used to make images of surfaces within cells

freeze cell, fracture w knife, and remove ice (etching) then layer platinum or carbon on the surface to make a replica

replica studied using EM

cryogenic EM

used to look at protein structure

a thin layer of protein is placed on a grid and cryogenically frozen

grid is placed in EM and the pattern of electrons is recorded

pyocin: freeze fracture

attaches to the cell wall of other bacteria via a spice. Contracts its collar to the baseplate, causing the inner tube to puncture the bacterium

cells share these features:

plasma membrane, lipid bilayer seperating cell contents from environment

cytoplasm, composed mostly of water and where the cell’s metabolic processes occur

DNA, genetic material that stores information for the cell’s activity in genes

prokaryote general features

found everywhere

no nucleus

no organelles

earliest and most primitive cells

prokaryote structure

polysaccharide capsule layer: protects against water loss and viruses (not all have)

cell wall: protextive layer that maintains cell shape, composed of secreted peptidoglycan (carb/protein complex)

plasma membrane: regulates passage of materials in/out

cytoplasm

special prokaryote features

pili: hair-like extensions used for attachment during conjugation (DNA transfer to other cells) (intracellular, connected to cell membrane)

flagellum: whip-like structure used for movement (intracellular, connected to cell membrane)

70s ribosomes: free floating, used mRNA templates to make proteins

DNA: naked, single, circular thread

plasmid: autonomously replicating small circle of DNA

eukaryotes general features

compartmentalization: nucleus, organelles

eukaryote features

plasma membrane

nucleus

80s ribosomes: free floating and bound to the ER, composed of proteins and rRNA. Uses mRNA template to make proteins

mitochondria

functions of life

metabolism

response

homeostasis

movement

growth

reproduction

excretion

nutrition

paramecium

unicellular protozoa

found in aquatic environments

heterotrophs

chlamydomonas

unicellular green algae

distributed all over the world

autotrophs

extra differences between animals, and plant

80s ribosome (both)

nucelus (both)

cell wall (plant)

chloroplasts (plants)

animal vs fungi vs plant

plastids: family of organelles w two outer membranes and internal membrane sacs (plants)

cell wall: chitin (fungi), or cellulose (plant)

vacuole: small in animal cells, large in fungi and plant

centrioles: spindle fibers for chromosome movement during cell division (animal)

atypical cells w more/less nuceli

red blood cells: no nuclei

phloem sieve tube elements: no nuclei

skeletal muscles: multi-nucelated

aseptate fungal hyphae: multi-nucleated. aseptate= w/out septate (dividing walls)