3.2.1.1 - structure of eukaryotic cells

name all the organelles in a eukaryotic cells

• cell-surface membrane

• nucleus

• mitochondria

• chloroplasts

• Golgi apparatus + Golgi vesicles

• lysosomes

• ribosomes

• rough endoplasmic reticulum + smooth endoplasmic reticulum

• cell wall

• cell vacuole

which organelles are unique to the plant cell

• vacuole

• cell wall

• chloroplasts

function of cell-surface membrane

• allows cell recognition and response

• controls movement of substances in and out

what is the cell surface membrane made of

• phospholipid bilayer (2 layers of phospholipid molecule

• each one has a phosphate head and 2 fatty acid tails

• tails face inward, forming a selectively permeable barrier

• prevents most polar (water-soluble) substances from passing through

what model describes how molecules are arranged in the cell surface membrane

• fluid mosaic model

• fluid describes the sideways (lateral) movement of particles

• mosaic describes the scattered arrangement of proteins within the bilayer

diagram of cell surface membrane

look in pictionary

what 2 things does the nucleus contain?

• chromatin —→ DNA associated with protein

• nucleolus —→ makes RNA and ribosomes

what is the nucleus surrounded by

what does the nucleus have that allows things to enter and leave

a nuclear envelope (double membrane)

nuclear pores

main function of mitochondria

to generate ATP through aerobic respiration

• what is the mitochondria surrounded by

• what is the inner membrane of the mitochondria folded into

• nuclear envelope (double membrane)

• cristae  —→ shelf-like extensions that provide larger SA for attachment of enzymes / proteins essential for aer. resp.

the matrix in the mitochondria is fluid-filled and contains…

• mitochondrial DNA 

• ribosomes 70s —→ to synthesise proteins involved in resp.

mitochondria also contains phosphate granules - what do these do?

help mitochondria make ATP by storing the phosphate needed for it

diagram of mitochondria

main function of the chloroplast

to carry out photosynthesis

• what does chlorophyll allow for?

• chlorophyll = stored in the t____________ m_____________. these form stacks called g________. granum are connected to other granum by l____________.

• efficient light energy absorption

• chlorophyll = stored in the thylakoid membranes. these form stacks called granum. granum are collected to other granum by lamellae. 

the chloroplast has a n__________ e___________ (double membrane)

nuclear envelope

the chloroplast contains its own…

what do the ribosomes enable the chloroplast to do

• DNA and ribosomes (70s)

• produce some of the proteins necessary for photosynthesis

where in the chloroplast does photosynthesis occur?

• thylakoid membranes

• stroma

what is the rough endolasmic reticulum (RER)

an extension of the nuclear envelope

network of folded membranes (which contain fluid) studded with ribosomes 

what is function of RER

• helps to synthesize, fold and modify proteins for secretion / insertion into membranes

• to  process and transport proteins

what are the interconnected, flattened membrane sacs called

what happens in these

cisternae

after proteins = synthesized by ribosomes, they are released into the cisternae, where they are folded into their correct shape + sometimes chemically modified.

they are then packaged into vesicles

what does the RER do when it performs a quality control check?

rejects / sends misfolded proteins for breakdown

function of the smooth endoplasmic reticulum (SER)

synthesizes and stores lipids and phospholipids for cell membranes

does the SER have any ribosomes?

no

what does the SER do that is essential for maintaining blood gluc. levels?

metabolises carbs, e.g. the breakdown of glycogen to glucose

what does the SER make in cells in the ovaries / testes

steroid hormones (e.g. oestrogen, testosterone)

what does the SER do in liver cells?

contains enzymes that break down toxins and drugs

how does the SER provide a larger SA for enzyme activity

• connects to the nuclear envelope

• forms a network through the cytoplasm

what does the SER do in muscle cells?

stores calcium ions, which are important for contractions

the SER can form t___________ v___________ that bud off from the SER’s surface to carry n_______ s_______________ p__________ / l________ to the G______ a_____________

the SER can form transport vesicles that bud off from the SER’s surface to carry newly synthesized proteins / lipids to the Golgi apparatus

main function of the Golgi apparatus and Golgi vesicles

• modifies / sorts proteins and lipids received from the ER (endoplasmic reticulum)

• packages them into Golgi vesicles for delivery to their final destinations (inside / outside cell)

what do Golgi vesicles do when they transport these molecules?

bud off from the Golgi

where do they get transported?

• to cell membrane for secretion (e.g. insulin)

• to other organelles in cell

• to get incorporated into cell membrane

• the Golgi body produces…

• what is a vesicle

• where are vesicles found on the Golgi body

• vesicles

• small, membrane-bound sac filled with fluid

• on the edge (at the trans face)

a type of Golgi vesicle (so produced by the Golgi apparatus) is the…

lysosome

function of the lysosome

acts as the cell’s waste disposal

what does the function of the lysosome entail (so explain how it performs its function in more detail)

• digests old / damaged organelles

• breaks down large molecules from outside cell into simpler soluble substances, so cell can absorb / use them

• destroys invading pathogens, e.g. bacteria

• what type of enzymes does the lysosome contain?

• what are these called?

• these are synthesized in the R___ + processed in the G_____ a___________, then packaged into the l______________.

• hydrolytic enzyme

• lysozymes

• these are synthesized in RER + processed in Golgi apparatus, then packaged in lysosome.

how does the membrane surrounding the lysosome protect the rest of the cell?

• keeps lysozymes contained

• protects the rest of the cell from these so it doesn’t get digested

KIND OF EXTRA?

• what do lysosomes fuse with in phagocytes?

• what are these?

• what do the lysosomes then do?

• phagosomes

• vacuoles in phagocytes that contain engulfed material, e.g.pathogens like bacteria

• breaks down these pathogens

function of the ribosome

• protein synthesis (i.e. translating mRNA into polypeptide chains)

structure of the ribosome

• no membrane

• made of 2 subunits - the large subunit and the small subunit

what 2 things is the ribosome made of?

• ribosomal RNA (rRNA)

• proteins

• what are the 2 types of ribosomes?

• which ones do eukaryotic cells have and which ones do prokaryotic cells have?

• what two organelles are the exception, and how?

• 70s (small) and 80s (large)

• eukaryotic cells = 80s ribosomes, prokaryotic cells = 70s ribosomes

• mitochondria and chloroplasts —→ they have 70s ribosomes (similiar to eukaryotic cells)

main function of the cell wall

• to provide structure + support

• to give cell a fixed shape

• to prevent cell from bursting under turgor pressure (from water intake via osmosis)

what does the permeable layer of the cell wall allow it do

allow for water / dissolved substances to pass through (substances can be exchanged with the environment)

what does the tough outer layer of the cell wall allow the cell to do

• withstand pressure

• support the cell

• prevent it from bursting

what is the cell wall made of in plants

cellulose

what is the cell wall made of in algae

cellulose, or glycoproteins

what is the cell wall made of in fungi

chitin (a polysaccharide, like cellulose)

what is the cell wall made of in bacterial cells

murein

what is the vacuole

a fluid-filled sac

function of the vacuole

• stores cell sap in plants

• helps maintain cell pressure and structure (keeps cell turgid)

what does cell sap do

• maintains turgor pressure to support the plant

• to prevent wilting (keeps plant rigid + upright)

KIND OF EXTRA?: list all the substances that make up cell sap

• water

• ions

• sugars + amino acids = act as a temp. food store

• salts

• wastes

• anthocyanins (pigments)

what do anthocynanins (pigments stored in the cell sap) do for the plant

provide colour for petals

• are there vacuoles in animal cells

• are they bigger or smaller

• what is their function there

• yes

• much smaller

• temp. storage of water / nutrients, transport and waste removal

what is the membrane that surrounds the vacoule called

what does this do

tonoplast

separates the vacuole’s contents from the cell’s cytoplasm