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bio 2.1 cell structure > 2.1.4 ultrastructure of eukaryotic cells: membrane-bound organelles > Flashcards

2.1.4 ultrastructure of eukaryotic cells: membrane-bound organelles Flashcards

1
Q

what do all eukaryotic cells have

A
  • nucleus surrounded by nuclear envelope & contains DNA organised/wound into linear chromosomes
  • nucleolus (contains RNA), inside nucleus, where chromosomes unwind & involved in making ribosomes
  • cytoplasm where organelles suspended
  • cytoskeleton
  • plasma membrane
  • membrane-bound organelles
  • small vesicles
  • ribosomes which assemble proteins
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2
Q

what’s a cytoskeleton

A

network of protein filaments (actin/microtubules) within cytoplasm that moves organelles from place to place in cell, allow some cells to move & allow contraction of muscle cells

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3
Q

types of protein filaments (eukaryotic)

A

actin or microtubules

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4
Q

structure of nucleus, nuclear envelope & nucleolus

A

nucleus:
- surrounded by double membrane (nuclear envelope)
- nuclear envelope has pores

nucleolus:
- no membrane
- contains RNA

chromatin:
- genetic material -> consists of DNA wound around histone proteins
- (not dividing) chromatin = extended/spread out
- (dividing) chromatin = condense/coils tightly into chromosomes

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5
Q

function of nucleus, nuclear envelope & nucleolus

A

(summary) nucleus:
- control centre of cell
- stores organism’s genome
- transmits genetic info
- provides instructions for protein synthesis

nuclear envelope:
- separates contents of nucleus from cell
- outer/inner membrane fuse in some regions = allow dissolved substances/ribosomes to pass through
- pores enable larger substances (eg. mRNA) to leave nucleus & enable substances (eg. steroid hormones) to enter nucleus

nucleolus:
- ribosomes are made

chromosomes:
- contain organisms gene

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6
Q

structure of rough endoplasmic reticulum (RER)

A
  • system of membranes
    –> contain fluid-filled cavities (cisternae) that are continuous with nuclear membrane
  • coated with ribosomes
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7
Q

function of rough endoplasmic reticulum (RER)

A
  • intracellular transport system
  • cisternae form channels for transporting substances around cell
  • large surface area for ribosomes to assemble amino acids to proteins
  • proteins then actively pass through membrane into cisternae & are transported to golgi apparatus for modification/packaging
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8
Q

structure of smooth endoplasmic reticulum (SER)

A
  • system of membranes
  • contain fluid-filled cavities (cisternae) continuous with nuclear membrane
  • no ribosomes on surface
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9
Q

function of smooth endoplasmic reticulum (SER)

A
  • contains enzymes that catalyse reactions involved with lipid metabolism
  • involved with absorption, synthesis & transport of lipids (from gut)
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10
Q

examples of reactions the enzymes in the SER catalyse

A
  • synthesis of cholesterol
  • synthesis of lipids/phospholipids (needed by cell)
  • synthesis of steroid hormones
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11
Q

structure of golgi apparatus

A
  • consists of stack of membrane-bound flattened sacs
  • secretory vesicles bring materials to/from
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12
Q

function of golgi apparatus

A
  • proteins are modified
  • proteins packaged into vesicles that are pinched off
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13
Q

examples of proteins modified by the golgi apparatus

A
  • adding sugar molecules to glycoproteins
  • adding lipid molecules to glycolipids
  • folded into 3D shape
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14
Q

what happens to the proteins (in vesicles) which are pinched off the golgi apparatus

A
  • stored in cell
    OR
  • move to plasma membrane to be incorporated into membrane or exported outside cell (exocytosis)
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15
Q

structure of mitochondria (single = mitochondrion)

A
  • spherical, rod-shaped or branched
  • surrounded by 2 membranes with fluid-filled space between
  • inner membrane folded into cristae
  • inner part of mitochondrion is fluid-filled matrix
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16
Q

function of mitochondria

A
  • site of ATP production (aerobic respiration)
  • self-replicating so more made if energy demand increases
  • abundant in cells where much metabolic activity occurs
17
Q

structure of chloroplasts

A
  • large
  • only in plant cells/some protoctists
  • surrounded by double membrane/envelope
  • inner membrane continuous with stacks of flatted membrane sacs (thylakoids) which contain chlorophyll
  • each stack/pile of thylakoids is called a granum
  • fluid-filled matrix = stroma
  • contain loops of DNA & starch grains
18
Q

plural of granum

A

grana

19
Q

function of chloroplasts

A
  • site of photosynthesis
  • 1st stage of photosynthesis occurs in grana & water split to supply H ions
  • 2nd stage occurs in stroma
  • abundant in leaf cells
20
Q

what part of the leaf are chloroplasts abundant in

A

palisade mesophyll layer

21
Q

structure of vacuole

A
  • surrounded by membrane = tonoplast
  • contains fluid
22
Q

function of vacuole (plant cells)

A
  • large & permanent vacuole
  • filled with water/solutes
  • maintains cell stability: full = pushes against cell wall, making cell turgid
  • turgid = support plant (especially non-woody plants)
23
Q

structure of lysosomes

A
  • small bags formed from golgi apparatus
  • surrounded by single membrane
  • contain powerful hydrolytic enzymes
  • abundant in phagocytic cells which ingest/digest invading pathogens
24
Q

another word for hydrolytic

A

digestive

25
Q

function of lysosomes

A
  • keep powerful hydrolytic enzymes separate from rest of cell
  • can engulf old cell organelles/foreign matter, digest & return digested components to cell for reuse
26
Q

structure of cilia/undulipodia

A
  • protrusions from cell
  • surrounded by cell surface membrane
  • contain microtubules
  • formed from centrioles
27
Q

function of cilia/undulipodia

A
  • epithelial cells lining airways beat/move band of mucus via cilia
  • nearly all cell types in body have 1 cilium acting as an antenna which contains receptors & allows cells to detect signals about immediate environment
  • only type of human cell with undulipodium = spermatozoon –> enables it to move

bio 2.1 cell structure (7 decks)

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