Eukaryotic and Prokaryotic cells Flashcards

1
Q

Nucleus, nuclear envelope and nucleolus structure

A

The nucleus surrounded by double membrane (nuclear envelope) containing pores
Nucleolus contains RNA (no pores)

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2
Q

Chromatin

A

Genetic material consisting of DNA wound around histone proteins
When cell is not dividing, chromatin is spread out/extended
When cell is about to divide, chromatin condenses and coils tightly into chromosome

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3
Q

Nucleus, nuclear envelope and nucleolus functions

A

Nuclear envelope separates contents of nucleus from rest of the cell
outer and inner nuclear membranes fuse together- dissolved substances and ribosomes can pass through
pores enable large structures eg. mRNA to leave nucleus
substances can enter the nucleus from the cytoplasm via pores
nucleus controls centre of the cell, stores organisms genome, transmits genetic info, provides instructions for protein synthesis

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4
Q

vesicles

A

a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer
form naturally during the processes of secretion, uptake, and the transport of materials within the plasma membrane.

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5
Q

Rough endoplasmic reticulum structure

A

System of membranes containing fluid filled cavities (cisternae) that are continous with the nuclear membrane
Coated with ribosomes (hence its roughness)

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6
Q

RER functions

A

transport system: cisternae form channels transporting substances from one area of cell to another
large SA for ribosomes which assemble amino acids into proteins
proteins actively pass through membrane into cisternae and are transported to golgi apparatus for modification and packaging

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7
Q

Smooth endoplasmic reticulum structure

A

system of mmebranes containing cisternae that are continuous with the nuclear membrane
no ribosomes on surface

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8
Q

SER functions

A

contains enzymes that catalyse reactions such as:
synthesis of cholesterol, synthesis of lipids/phospholipids, synthesis of steroid hormones
involved with absorption, synthesis, and transport of lipids (from gut)

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9
Q

Golgi apparatus structure

A

stack of membrane-bound flattened sacs
secretory vesicles bring materials to and from the golgi apparatus

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10
Q

Golgi apparatus function

A

Proteins are modified by:
adding sugar molecules to make glycoproteins
adding lipid molecules to make lipoproteins
being folded into their 3D shape
The proteins are packaged into vesicles that are pinched off and then:
stored in the cell
moved to plasma membrane

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11
Q

Mitochondria structure

A

Spherical, rod-shaped or branched, and are 2-5µm
surrounded by two membranes with a fluid-filled space between them
inner membrane is highly folded into cristae
inner part of the mitochondrion is fluid-filled matrix

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12
Q

Mitochondria function

A

site of ATP (energy currency) production during aerobic respiration
self-replicating, so more can be made if the cell’s energy needs to increase
abundant in cells where metabolic activity takes place

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13
Q

Chloroplasts structure

A

large organelles, 4-10µm
surrounded by double membrane/envelope
inner membrane is continuous with stacks of flattened membrane sacs (thylakoids) containing chlorophyll
contains loops of DNA and starch grains

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14
Q

chloroplasts function

A

site of photosynthesis
abundant in leaf cells- particuarly the palisade mesophyll layer

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15
Q

Vacuole structure

A

surrounded by a membrane (tonoplast) containing fluid

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16
Q

vacuole function

A

filled with water and solutes and maintains cell stability
only plant cells have permanent vacuoles

17
Q

Lysosomes structure

A

small bags formed from the golgi apparatus
surrounded by a single cell membrane
contains powerful hydrolytic (digestive) enzymes

18
Q

Lysosome function

A

Keeps hydrolytic enzymes separate from rest of cell
engulfs old organelles and foreign matter, and digests them, returning digested components to the cell for reuse

19
Q

Cilia and undulipodia structure

A

protrusions from cell surrounded by cell surface membrane
contains microtubules
formed from centrioles

20
Q

Cilia and undulipodia function

A

cilia beats and moves band of mucus in epithelial cells
cilium contains receptors that allows the cell to detect signals in its immediate environment

21
Q

ribosome structure

non-membrane bound

A

small spherical organelles, 20nm in diameter
made of ribosomal RNA
made in nucleolus, passes through nuclear envelope into cell cytoplasm

22
Q

ribosome function

A

bound to exterior of RER to synthesise proteins
ribosomes free in cytoplasm are the site of assembly of proteins used inside cell

23
Q

Centriole structure

non-membrane bound
does not contain DNA

A

two bundles of microtubules at right angles to eachother
microtubules made of tubulin an protein subunits, arranged to form a cylinder

24
Q

Centriole function

A

involved in formation of cilia and undulipodia
organises microtubules that serve as the cell’s skeletal system
help determine the locations of the nucleus and other organelles within the cell.

25
cytoskeleton structure | non-membrane bound
network of protein filaments (actin or microtubules) within cytoplasm rod-like microfilaments made of subunits of protein actin (7nm in diameter) intermediate filaments 10nm in diameter straight, cylindrical microtubules made of protein subunits (tubulin) 18-30nm in diameter
26
cytoskeleton function 1
move organelles within the cell, allow some cells to move, and allow contraction of muscle cells keeps cell shape stable microtubules provide shape and support to cells and help substances and organelles move through cytoplasm form the spindle before a cell divides, enabling chromosomes to be moved within the cell
27
cytoskeleton function 2
microtubules make up cilia, undulipodia and centrioles enables cell to cell signalling, allowing cells to adhere to a basement membrane and stabilises tissues intermediate filaments are made of a variety of proteins which anchor the nucleus within the cytoplasm, extend between cells in tissues and special junctions
28
cellulose cell wall structure | non-membrane bound
on the outisde of plasma membrane made from bundles of cellulose fibres
29
cellulose cell wall function
prevents plant cells from bursting when turgid provides plant cells with strength and support, maintenance of cell shape, strength and support of plant, permeable and allows solutions to pass through
30
prokaryotic cell wall structure
made of peptidogylcan instead of cellulose
31
How are proteins made and secreted (using example of how insulin is made in beta cells)
mRNA copy of instructions (gene) for insulin is made in the nucleus mRNA leaves nucleus though nuclesr pore mRNA attaches to ribosome (eg on RER) ribosome reads instructions to assemble protein insulin molecules are 'pinched off' in vesicles and travel to golgi apparatus vesicles fuse with golgi apparatus golgi apparatus processes and packages insulin molecules for release packaged insulin molecules are pinched off in vesicles from golgi apparatus and move towards plasma membrane vesicles fuse with plasma membrane plasma membrane opens to release insulin molecules outside
32
comparing prokaryotic and eukaryotic cells (similarities)
both have: plasma membrane cytoplasm ribosomes for assembling amino acids into proteins DNA and RNA
33
comparing prokaryotic and eukaryotic cells (differences)
prokaryotic cells are much smaller P cells have a less well-developed cytoskeleton with no centrioles P cells have no nucleus P cells have no membrane-bound organelles, eg. mitochrondria, endoplasmic reticulum, chloroplasts or golgi apparatus P cells have a wall made of peptidoglycan (not cellulose) have smaller ribosomes naked DNA not wound around histone proteins
34
Prokaryotic cells (extra structures)
waxy capsule surrounding cell wall small loops of DNA (plasmids) and a main large loop of DNA flagella- allows bacteria to move (structure differs from eukaryotic undulipodia) pili- smaller hair-like projections that enable bacteria to adhere to host cells or to eachother, and allow passage of plasmid DNA from one cell to another
35
By what process do prokaryotic cells divide
Binary fission