(02) Cell Structure and Function Intro Flashcards

1
Q

Three principles of cell theory

A
  1. All living organisms are composed of one or more cells
  2. the cell is the basic unit of structure and organisation
  3. All cells arise only from pre-existing cells
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2
Q

prokaryotic and eukaryotic cells both have:

A

plasma membrane
cytosol
DNA
RNA
protein
ribosomes

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3
Q

difference between prokaryotic and eukaryotic cells

A

eukaryotic cells have Membrane-bound organelles
prokaryote cells lack a membrane- bound nucleus

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4
Q

define cytoplasm

A

everything inside the plasma membrane including organelles but NOT including the nucleus

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5
Q

define cytosol and its composition

A

the fluid portion of the cytoplasm
water + dissolved ions, ATP, protein, lipids

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6
Q

name the organelles in the endomembrane system

A

Nucleus
Endoplasmic Reticulum (smooth + rough)
Golgi apparatus
Lysosomes

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7
Q

name the six major organelles

A

nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes

Mitochondria
Ribosomes

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8
Q

define plasma membrane

A

a selectively permeable barrier controlling the passage of substances in and out of the cell

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9
Q

what makes up the plasma membrane

A

phospholipid bilayer with embedded proteins

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10
Q

parts of a phospholipid

A

hydrophilic polar heads (phosphate)
hydrophobic lipid tails (fatty acids)

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11
Q

define amphipathic

A

having both hydrophilic and hydrophobic regions

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12
Q

what are integral proteins

A

proteins embedded (partially or fully) into membrane

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13
Q

define transmembrane proteins

A

integral membrane proteins that fully span membrane
contact both extracellular and cytoplasmic areas

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14
Q

name the six cell specific dynamic repertoire of plasma membrane proteins

A

transport
enzymatic activity
signal transduction
cell-cell recognition
intercellular joining
attachment (to cytoskeleton and ECM)

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15
Q

define transduction

A

the process of moving genetic material

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16
Q

how does cell-cell recognition work?

A

use of glycoproteins (carb + plasma membrane protein) as molecular signature on extracellular side

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17
Q

how do PM proteins help attachment to cytoskeleton and ECM

A

eg. fibronectin mediates contact between cell surface integrals and ECM

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18
Q

define membrane

A

a mosaic of molecules in a fluid bilayer of phospholipids
(the fluid mosaic model)

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19
Q

structure of the nucleus

A

enclosed by double lipid bilayer = nuclear envelope
continuous with rough ER
nuclear pores - for entry / exit
Nucleolus in centre
network of chromatin

20
Q

what is chromatin

A

a mixture of DNA and proteins that form chromosomes

21
Q

functions of the nucleus

A

house/protect DNA
make rRNA and assemble ribosomes
pores regulate movement of substances (protein, mRNA)
molecule segregation allows temporal and spatial control of cell function

22
Q

what are ribosomes

A

made of ribosomal RNA (rRNA) and proteins
the site of protein synthesis (translation) in the cell
reads messenger RNA

23
Q

storing DNA in the nucleus - structure

A

DNA wrapped 2x around a group of 8 histones
–> nucleosomes
many nucleosomes –> chromatin

most of the time, DNA is present as chromatin and chromatin fibres

24
Q

structure of chromosomes

A

as cell prepares for cell division, chromatin –> chromatin fibres –> loops –> chromosomes

comprises many genes

25
Q

what is a gene

A

a DNA segment contributing to phenotype / function

26
Q

describe the structure and location of ribosomes

A

two subunits - large and small
subunits assemble in nucleolus and leave through nuclear pores

either:
free in cytoplasm (making proteins for cytosol)
OR attached to RER

27
Q

what is endoplasmic reticulum

A

an extensive network of tubes and tubules stretching out from the nuclear membrane

two types: rough / smooth

28
Q

describe the structure / location of rough endoplasmic reticulum

A

continuous with nuclear envelope
dotted with RIBOSOMES

29
Q

function + processes of rough endoplasmic reticulum

A

ribosomes –> production of secreted, membrane and organelle proteins

proteins enter lumen within RER for folding
RER membrane surrounds protein –> transport vesicles destined for the Golgi

30
Q

structure and location of smooth endoplasmic reticulum

A

extends from the rough ER
LACKS ribosomes

I think it looks a bit like coral

31
Q

functions of smooth ER

A

very cell/tissue type specific - hence functions vary greatly

housing unit for (cell specific) proteins and enzymes
synthesises lipids (incl steroids and phospholipids)

32
Q

function of Golgi apparatus

A

modify, sort, package and transport proteins received from the rough ER using enzymes

formation of secretory, membrane and transport vesicles

33
Q

structure of Golgi apparatus

A

made up of 3-20 flattened membranous sacs = cisternae
stacked on top of one another

cis face = receiving side
trans face = shipping side

34
Q

what are lysosomes

A

vesicles formed from Golgi membrane
contains powerful digestive enzymes - hence VERY ACIDIC

35
Q

main functions of lysosomes

A

digests / destroys substances that enter a cell, cell components, entire cells

36
Q

define autophagy

A

digestion of cell components (by lysosomes)
(for removing damaged organelles or misfolded proteins)

37
Q

define autolysis

A

cell self-destructs due to injury / dying tissue
(esp in lysosomes)

38
Q

describe the structure of mitochondria

A

outer membrane
inner membrane, with folds called cristae
matrix = fluid filled interior cavity

39
Q

mitochondria carry a separate ……

A

a separate small (37 genes) genome encoding mitochondrial specific products

40
Q

ATP hydrolysis equation

A

ATP –> ADP (adenosine diphosphate) + phosphate
+ Energy (released)

41
Q

name the three types of filaments in the cytoskeleton and their diameters

A

microfilaments - 7nm
intermediate filaments - 8-12nm
microtubules - 25nm

42
Q

describe the structure of protein in microfilaments

A

actin molecules assembled in two long chains, twisted around each other
found in the periphery of interior cell

assembled and disassembled as required = DYNAMIC

43
Q

function of microfilaments

A

bears tension + weight
anchors cytoskeleton to PM proteins

44
Q

functions and features of intermediate filament

A

bears tension and weight throughout cell
scaffolds cellular organelles
keratin

MOST PERMANENT - less dynamic

45
Q

describe the structure of microtubules

A

tubular structure - 25nm, centre lumen 15nm
made of coiled TUBULIN dimers (alpha and beta)
branched from centrosome

assembled and disassembled as required - DYNAMIC

46
Q

functions of microtubules

A

supports cell shape / size
guides movement of organelles (eg. vesicles from Golgi to membrane)
chromosome organisation - cell division
movement of cilia / flagella