IB Bio SL - Cells

prokaryotic cell

simple, small structure and no membrane bound organelles. includes bacteria and archaea.

typical components of prokaryotic cell

capsule, cell wall, cell membrane, pili, 70s ribosomes, nucleoid region, flagellum, and plasmids

eukaryotic cell

complex, larger, with membrane bound organelles. includes animal, plant and fungi cells.

typical components of eukaryotic cells

nucleus, nucleolus, cell membrane, smooth ER, rough ER, 80s ribosomes, mitochondria, golgi body, vesicles, lysosome. plant cells have all of these + cell wall, large central vacuole, and chloroplasts

stages of the cell cycle / PMAT

prophase - PREPARE for division

metaphase - chromosomes line up in the MIDDLE

anaphase - chromosomes pulled APART
telophase - TWO nuclei formed

what is the cell theory

1. cells compose all living things

2. cells are the basic structure of life

3. cells come from preexisting cells

exceptions to the cell theory

• striated muscle cells (many nuclei)

• giant algae (extremely big single cell)

• aseptate fungi (many nuclei)

• red blood cells (no nucleus)

microscopy

light, electron. techniques include: freeze fracture (cyrogenic EM) and immunofluorescence staining

light vs electron microscopy

light

• uses light and glass lenses

• live and ded cells

• lower magnification

electron

• electronbeams and electromagnetic lenses

• much higher magnification

• only dead cells

life processes / MR SHENG

metabolism

reproduction

stimuli

homeostasis

excretion

nutrition

growth

nucleus

large round double membrane structure with pores, stores DNA

golgi

stacks of flattened disks, modifies and packages proteins to be exported

mitochondria

double membrane, folded inner. produces ATP through aerobic respiration

lysosome

contains digestive enzymes for breaking down (only in animals)

smooth ER

folded squiggle, site for lipid synthesis and detox

rough ER

folded squiggle w ribosomes attached, site of protein synthesis

chloroplast

conduct photosynthesis (plants only)

vacuole

plants: have a large central vacuole that stores nutrients

animals: small vacuoles which help w waste removal

cell fractionation

• cells are broken open to releast their contents

• put into a solution

• blended/homogenized to create uniform mixture

• filtered with a centrifuge which separates organelles according to density

totipotent stem cells

has the potential to differentiate into all other cell types, including embryos. ie zygotes.

pluripotent stem cells

has the potential to differentiate into all cell types other than embryos. ie embryonic stem cells.

multipotent stem cells

has the potential to differentiate into a range of similar/related cells.

differentiation

stem cell specialization into certain cell type by expressing some genes and not others.

davson danielli model

lipid bilayer flanked by layers of proteins, originally supported by electron micrographs

singer nicholson/fluid mosaic model

lipid bilyaer with proteins embedded within

why was davson danielli model doubted?

1. proteins come in many different sizes, shapes, and types. likely would not be able to make a cohesive layer.

2. model would not be flexible, doesn’t account for the fluidity of the membrane

3. proteins are often hydrophobic, wouldn’t make sense to be on the outside layer

how was singer nicholson model supported?

1. freeze fracturing revealed a 3d view of the membrane, which had bumps of proteins sticking out.

2. fluorescent markers showed proteins moving within the membrane.

amphipathic

having both hydrophillic and hydrophobic properties.

components of membrane

• phospholipid - amphipathic molecues, hydrophillic heads and hydrophobic tails.

• channel protein - allow simple soluble molecules to pass thorugh

• peripheral protein - on the periphery of the membrane, hydrophillic, involved in cell to cell interactions/signaling.

• carrier protein - open to only 1 side of the membrane, for transport against the concentration gradient.

• glycoprotein - has carb chains, carry out variety of functions (receptors, structure, recognition)

• cholesterol - controls fluidity, permeability of membrane

diffusion

passive movement of particles following concentration gradient

facilitated diffusion

passive, charged ions pass through channel proteins

ie Na and K ions in nerve cells

osmosis

passive diffusion of water through semi-permeable membrane

hypertonic

more solute outside → water moves out → cell shrinks

hypotonic

more solute inside → water moves in → cell expands

hippo = big

isotonic

equal osmolarity, no net movement of water

active transport

movement across the membrane using energy/ATP and protein pumps

exocytosis

active process of vesicle containing material waste fuses w membrane and then releases it. “exit”

endocytosis

active process of taking in substances to the cell, “enter”