life at the cellular level (1) - cells Flashcards

1
Q

what is the cell

A

the functional unit of all living things
It is composed of cells and each cell is a membrane-bound volume of cytoplasm, containing DNA with the necessary genetic information to direct the development of the cell

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2
Q

how many cells do all organisms consist of

A

one or more

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3
Q

how do cells arise

A

all cells only arise from pre-existing cells

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4
Q

what do all cells have

A

a cell membrane and cel organelles

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5
Q

what are cell organelles

A

the machinery of the cell

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6
Q

what must all substances entering or leaving the cell cross

A

the cell membrane

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7
Q

List the features common to most cells

A
Plasma membrane
Cytoplasm
Cytosol
Ribosomes
Nucleus (eukaryote)
Nucleoid (prokaryote)

Eukaryotic cells possess a complex cytoskeleton and is organised into internal compartments

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8
Q

what are the domains of life

A

prokaryotes
eukaryotes
archea (but we will not be looking at this)

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9
Q

what domain of life do human cells belong to

A

eukaryotes

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10
Q

what domain of life do bacterial cells belong to

A

prokaryotes

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11
Q

what domain of life do multicellular animal and plant cells belong to

A

eukaryotes

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12
Q

what do eukaryotic cells contain

A

nucleus with membrane

membrane bound organelles

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13
Q

what do prokaryotic cells contain

A

lack nuclear membrane
no mitochondria
no membrane bound organelles

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14
Q

what are stem cells

A

cells that can differentiate into many (multipotent) or any (pluripotent) cell types of the body

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15
Q

why are stem cells clinically of great interest

A

as recent advancements in medical science now allow stem cells to be used in the treatment of certain diseases including some cancers

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16
Q

what can undifferentiated stem cells do

A

divide and give rise to daughter cells

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17
Q

what do differences in gene expression and the local cellular environmental cause

A

the daughter cells to develop into different cell types

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18
Q

what is apoptosis

A

controlled, programmed cell death

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19
Q

is apoptosis a normal process

A

yes, it is a normal process and essential for normal finction

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20
Q

what is apoptosis intimately coupled with

A

cell proliferation

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21
Q

what is cell proliferation

A

the process by which a cell grows and divides to produce two daughter cells

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22
Q

what is a loss of balance between apoptosis and proliferation associated with

A

some cancers

23
Q

what is necrosis

A

it describes the untimely death of cells in response to injury or infection

24
Q

is necrosis a normal process

25
what are cancer cells
they divide with out any control fail to coordinate with normal cells fail to differentiate into specialised cells displace and replace the normal cells - if not stopped
26
what is the cell membrane
Sometimes called the plasma membrane or plasmalemma Comprises a double layer of lipid with attached phosphate groups = phospholipid bilayer Forms a selective barrier, (being choosy about what it allows to cross in or out of the cell) Embedded in the membrane are proteins which act as receptors to detect chemical messengers and signalling molecules in the fluid surrounding cells (extracellular fluid)
27
cells are very small, more than 200 red blood cells could fit easily on a pin head, why is being small advantageous
there is a high surface are to volume ratio meaning there is a lot more surface are for substances to enter and leave the cell, making the work of the cell more efficient
28
what is the nucleus
Contains DNA, nucleoprotein and some RNA Nucleoli are sites of ribosomal RNA synthesis and ribosomal assembly The nucleus is enclosed in the nuclear membrane which, like all biological membranes, is a phospholipid bilayer. It is closely associated with the Rough Endoplasmic Reticulum
29
what are the different types of endoplasmic reticulum (ER)
rough (RER) and smooth (SER)
30
why is it called the rough ER
because it has ribosomes attached giving it the "rough" appearance
31
what do ribosomes do
synthesise proteins
32
what does the RER do
modifies proteins
33
what does the SER do
SER has no ribosomes attached and is mainly associated with lipid and steroid hormone production and metabolism of toxins
34
what does the golgi apparatus do
packages up protein (including enzymes) in preparation for transport out of the cell
35
what is the structure of the mitochondria
Mitochondria are organelles bound by a phospholipid bilayer Outer membrane contains pores Inner membrane has cristae (folds) Matrix contains most of the enzymes required for metabolising food molecules (e.g. Krebs cycle)
36
what is the golgi aparatus
a membrane bound organelle | a series of flattened membrane discs
37
what is the endoplasmic reticulum
a membrane bound organelle | forms a network of membrane tubules continuous with the nuclear membrane
38
facts about the mitochondria
They have their own circular DNA They have their own ribosomes – similar to bacterial ribosomes They synthesise most of their own proteins They can self-replicate
39
what are enzymes
one form of protein packages by the golgi apparatus
40
what do enzymes do
catalyse reactions in cells but need to be stored untill needed
41
what are lysosomes
membrane bound vesicles containing enzymes - they separate enzymes from the rest of the cell
42
when/where are lysosomes used
in autophagy (digestion of cells own materials) or digestion of engulfed particles (e.g. bacteria)
43
what is the cytoskeleton
Supports and maintains cell shape Holds organelles in position Helps move organelles around the cell It is compromised of one of three forms of protein
44
what are the three forms of protein
microfillaments intermediate fillaments microtubules
45
what form of protein is the cytoskeleton made of
microtubules
46
what are microfillaments
made up of strands fo the protein actin | often interact with stands of other proteins
47
what are intermediate filaments
made up of fibrous proteins organised into tough, rope-like assemblages that stabilize a cell's structure and help maintain its shape
48
what are microtubules
long, hollow cylinders made up of many molecules of the protein tubulin.
49
what is tubulin
consists of two subunits α-tubulin and β-tubulin
50
what do some cells have that is supported by the cytoskeleton
surface projections
51
what are cilia and eukaryotic flegella made of
microtubules
52
what is cilia
short, usually many present, move with stiff power stroke and flexible recovery stroke
53
what is flagella
longer, usually one or two present, movement is snakelike