structure of pro and eukaryotic cells 1

organisms vs viruses

• organisms can:

• reproduce

• respond to stimuli

• transform matter and energy

• display homeostasis

why are cells so similar?

• all cells have the same common ancestor: ancestral prokaryote

• prokaryotes gave rise to eubacteria and archaea bacteria

• later mitochondria and chloroplasts merged with a single prokaryotic cell

• gave rise to animal and fungi cells

• later on merged with another bacterium which could undergo photosynthesis → plant cells

prokaryotes give rise to two types of bacteria:

• eubacteria

• 'true bacteria'

• live in environments familiar to humans

• i.e. E. coli is a gut bacterium

 

• archaea bacteria

• found in hostile environments

prokaryote features

• no nucleus

• plasma membrane

• cell wall

• circular DNA in ribosomes

• no membrane-bound organelles

• flagellum

energy sources used by prokaryotes (list 3)

• organotrophic → organic molecules

• phototrophic → light

• lithotrophic → inorganic molecules

eukaryotes (unicellular vs multicellular examples)

• unicellular → protists and yeast

• multicellular → animals, plants and fungi

prokaryote vs eukaryote structure

• eukaryotes:

• plasma membrane

• cytoplasm

• cytoskeleton

• nucleus

• mitochondria

• chloroplasts

• ribosomes

• endoplasmic reticulum

• golgi body

• prokaryotes:

• plasma membrane

• cytoplasm

• cytoskeleton

• ribosomes

• cell wall

prokaryotes lack (?) organelles

membrane-enclosed

ribosomes

• prokaryotes and eukaryotes

• two populations in eukaryotes

• cytosolic → free or attached to endoplasmic reticulum

• in mitochondria or chloroplasts

cytoskeleton

• prokaryotes and eukaryotes

• cell structure and allows cell to keep its shape and organise itself

• in eukaryotes: 3 types of filamentous structures

1. actin filaments

2. intermediate filaments

3. microtubules

actin filaments

• change the shape of tissue cells (fibroblasts)

• cell movement → allow animal cells to migrate

intermediate filaments

• made up of intermediate filament proteins

• strong and rope-like

• cytoplasmic → keratin filaments

• nuclear → organise shape of nucleus and provides attachment sites for chromosomes

microtubule filaments

• organise the cytoplasm

• intracellular transport

• allow cell movement

• forms mitotic spindle to separate chromosomes during cell division

plasma membranes

• cell signalling

• transport of solutes

• cell movement

• cell growth

• semi-permeable membrane

single membraned vs double membraned

• single membraned

• plasma membrane

• endoplasmic reticulum

• golgi body

• transport vesicles

• double membraned

• nucleus

• mitochondria

• chloroplasts

plasma membranes are selective barriers: what molecules can and can’t cross?

Small nonpolar molecules can cross freely

• Oxygen

• Carbon dioxide

 

Small uncharged polar molecules can cross freely

• Water

• Ethanol

 

Large uncharged polar molecules can hardly cross

• Glucose

• Amino acids

• Nucleosides

 

Charged molecules and ions cannot cross

Can cross with transmembrane proteins

• Na+

• K+

• Cl-

name two plasma membrane carbohydrate groups

• glycolipids

• glycoproteins

plasma membrane carbohydrate groups function

• cell-to-cell communication

• protection from chemical and mechanical damage

• cell adhesion

glycolipids vs glycoproteins

• glycolipids

• carbohydrate group attached to lipids

• glycoproteins

• carbohydrate group attached to proteins