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Biology MDCAT > Cell Structure and Function > Flashcards

Cell Structure and Function Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

which types f organisms have cell walls

A

plants, prokaryotes and fungi

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2
Q

why dont animal cells have cell walls

A

prob due to their locomotor mode of life

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3
Q

plant cell walls are made up of

A

cellulose

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4
Q

cell wallls of prokaryotes are made of

A

petidoglycan

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5
Q

fungi cell wall is made

A

chitin

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6
Q

the cell wall is ———— permeable

A

FULLY

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7
Q

enlist the three layers of cell wall

A

PRIMARY CELL WALL
MIDDLE LAMELLA
secondary cell wall

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8
Q

primary cell wall develops during

A

cell division in a newly growing cell

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9
Q

describe the structural properties of primary cell wall

A

thin and flexibl

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10
Q

what is primary cell wall composed of

A 
cellulose microfibrils (bundles of cellulose chains) running through a matric of polysaccharides such as hemicellulose and pectin. 
crisscross arrangment of of microfibrils in layer
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11
Q

which feature gives cell wall its stength

A

crisscorss arrrangemnt of microfibrils

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12
Q

the primary cell wall is well adapted to ————

it stretches —————

A

growth

plastically (irreverably)

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13
Q

where is the secondary cell wall formed

and in which cells

A

between primary cell wall and cell membrane only in sclerenchyma cells

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14
Q

generally which cells posses secondary cell wall

A

dead cells

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15
Q

cell containing secondary cell wall are for which purpse

A

support

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16
Q

when does secondary cell wall deveop

A

whwen the cell has reached max size

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17
Q

why does secondary cell wall develope only when the cell ahs reach ax size

A

secondary cell wall is thick and ridged and does not allow or further growth

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18
Q

what is the chemical composition of secondary cell wall

A

cellulose,hemicelluose, lignin, inorganic salts and waxes

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19
Q

describe the structure of secondary cell wall

A

crisscros arrangement of microfibrils

lignin cements and anchors microfibrils together(responsible for ridgidness0

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20
Q

what is the purpose of secondary cell wall

A

provides definite shape and support to cell

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21
Q

where is middle lamella of cell wall present and what is its function

A

between primary cell walls of adjacent cells

hold the cells together

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22
Q

what is middle lamella composed of

A

sticky ,
gel like magnesium and calcium salts
pectin

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23
Q

plasma membrane is the boundary of —————-

A

protoplasm

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24
Q

in whcih cells is plamsa membrane found

A

al living prokaryotic and eukaryotic cells

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25
Q

what is the composition of plasma membrane

A

60-80% proteins
20-40% lipids
and small quantity of carbohydrates

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26
Q

what is fluid mosaic model

A

membrane is a phospholipid bilayer
proteins are partially/ completely embedded in it

proteins are scattered in an irregular pattern

looks like large icebergs floating in the sea

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27
Q

what is the thickess of plasma membrane

A

7nm

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28
Q

describe the lipid bilayer of plasma membrane

A

phospholipids hydrophilic heads face the surface and hydrophilic tails face each other

steroids, cholesterol are wedged between phospholipids at intervals

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29
Q

internal and external surface of plamsa membrane is not

A

identical

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30
Q

——————– determines most of the functions of plasma membrane

A

proteins, glycoproteins, glycolipids

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31
Q

what supports the plasma membrane and where is it present

A

cytoskeleton which is attached to inner surface of plasma membrane

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32
Q

what are the functions of plasma membrane lipid

A

controls the fluidity of the membrane

conc of unsaturatted fatty acids in phospholipids increase the bilayer becomes more fluid and plasma membrane more flexible

cholesterol helps stabilize the lipid bilayer

restricts entry and exit of polar molecules and ions

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33
Q

what is the function of proteins in cell membrane

A

may act as channel, carreir protein
enzyme
receptor
antigen

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34
Q

what is the function of glycolipids and glycoproteins in cell membran

A

as cell surface antigens
cell to cell recognition
cell to cell adhesion

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35
Q

transport occurs across the plasma membrane to

A

obtain nutreints
secrete useful surbsatnces
geenerate ionic gradients for nervous and muscularr activity
excrete waste products
maintain suitable pH and ionic concentration for optimal enzyme activity

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36
Q

the living matter of cell is called

A

protoplasm

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37
Q

where and in which cells is cytoplasm present

A

in between plasma membrane and nucleus

in eukaryotic and prokarytoic cells

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38
Q

describe the composition of cytoplasm

A

salts,sugar,amino acids fatty acids, nucleotides, vitamins and dissolved gases are in form of true solution

proteins, and large molecules form colloidal solutions

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39
Q

what is cytosol and its location

A

inner portion of cytoplasm towards the nucleus which is less viscus

40
Q

what is cytogel and its location

A

peripheral portion of cytoplasm which is more viscous

41
Q

what is cyclosis and its purpose

A

circular streaming movement in cytoplasm due to contractile activity of microfilaments

it is responsible for distribution of contents in cytoplasm

42
Q

what are organelles

A

highly organized discrete structures specific for carious cellular functions generally enclosed in a membrane except for ribosomes

43
Q

what is endoplasmic reticulum

A

an interconnecting network of cisternae (elongated closed sacs) which extend from nuclear membrane to plasma membrane throughout the cytoplasm of all eukaryotic cells

44
Q

describe RER along with its function

A

endoplasmic reticulum with ribosomes attached to it on the side facing the cytoplasm

mainly concerned with proteins synthesis
provides mechanical support to the cell

45
Q

describe smooth ER along with its functions

A

it is continuous with RER
does not have ribosomes
smooth appearance

metabolism of carbs 
detoxification of drugs/ poisons
synthesis of lipids (oils, phospholipids, steroids)
stores calcium for muscular contraction 
transport to golgi apparatus
provides mechanical support  to cell
46
Q

when was golgi apparatus discovered and by who

A

camillo golgi

1898

47
Q

describe the structure of golgi body

A

stack of flattened membrane bound sacs (cisternae) together with system of associated vesicles (Golgi vesicles)

48
Q

what is cis face of golgi body

A

forming face / convex face/ outer face

49
Q

what is trans face

A

maturing face/ concave face/ innner face

50
Q

what is the funtion of golgi body

A

processing cell secretions mainly proteins
lysosomes, peroxisomes and glyoxysomes originate from Golgi body
involved in formation of glycoprotein, glycolipid
in plants it gives rise to vesicle which contain cell wall synthesizing materials

51
Q

how is phragmoplast formed and what is its function

A

during cytokinesis golgi vesicles arranged at equator fuse together to form it

new cell wall is derived from it

52
Q

what are lysosomes and what does they contain

A

single membranous, spherical vesicles containing digestive and hydrolytic enzymes

53
Q

how are lysosomes formed

A

their enzymes are formed by RER, transported to golgi body by SER
after modification they are released rom trans face in the form of vesicles

54
Q

what s primary lysosome

A

newly formed lysosomes before the start of their functions

55
Q

what are secondary lysosomes

A

endosomes that fuse with primary lysosomes

56
Q

what are endosomes, phagosomes, autophagosomes

A

vesciles formed by endocytosis
vesciles formed by phagocytosis
vesicles formed by autophay

57
Q

what are the major functions of lysosomes

A

intracellular digestion
autophagy
autolysis
release of extra cellular enzyes

58
Q

what is contractile vacuole

A

secondary lysosome containing waste products after digestive materials have been absorbed by cytoplasm

59
Q

what is intracellular digestion

A

ingestion of food vacuole
fusion primary lysosome with food vacuole to form secondary lysosome
formation of contractile vacuole
exocytosis of undigested waste products

60
Q

what is autophagy

A

process by which unwanted structure within cell are engulfed and digested within lysosomes

61
Q

what is autolysis

A

cell death when a particular cell is required to be disintegrate

62
Q

describe autolysis

A

lysosome burst their enzymatic contents disperse throughout the cell cytoplasm
cell disintegrates into fragments which are phagocytosed by other cells

63
Q

what are lysosomal storage diseases

A

accumulation of various substances in the cell due to absence or lack of lysosomal enzymes

64
Q

nature of lysosomal storage disease is

A

hereditary and congenital

65
Q

how many lysosomal storage diseases have been indentified

A

20

66
Q

what is one common example of lysosomal storage disease

A

lipid digesting enzymes is missing or inactive

brain becomes impaired due to accumulation of lipids in cells

67
Q

what are vacuoles

A

large vesicles originating from endoplasmic reticulum, gogli body and plasma membrane

68
Q

what are the functions of vacules in organisms except plants

A

in animals food vacuoles are formed by phagocytosis

in fresh water protocists contactile vacules pump exess water out of cell

69
Q

describe function and structure and development of vacuoles in plants

A

hold reserves of inorganic compound for

protection against herbivores (poison/unpleasant)
mechanical support
turgor

large central vacuole
containing cell sap
its membrane is tonoplast

it develops by joining of smaller vacuoles

70
Q

the number of mitochodira in a cell coorelates with

A

the cels level of metabolic activity

71
Q

how are new mitochondria formed

A

self replicate by fission

72
Q

describe the shape of mitochodria

A

they ae cylindrical or rod shaped

73
Q

describe the structure of mitochondria

A 
it has two membranes 
outer membrane has porins 
inner membrane space 
inner membrane has fold called cristae 
cristae contain F0-F1 particles (ATP synthase)
mitochondrial matrix
74
Q

what is the function of porins in outer membrane of mitochondria

A

they allow free passage of various molecules into intermembrane space

75
Q

describe the composition of mitochondrial matrix

A 
jelly like material
contains circular DNA 
all kinds of RNA 
ribosomes (70S)
enzymes
76
Q

where are plastids found

A

plant and algal cells

77
Q

why are plastids essential

A

necessary for photosynthesis and food storage

78
Q

plastids are classified into

A

proplastids, leucoplasts, chromoplasts and chloroplast

79
Q

what are proplastids

A

young immature and developing plastids

they are self replicating organelles
divide and re-divide in meristematic cells
they are distributed in different cell types
they develop either into chloroplasts or leucoplasts depending on their exposure to light

80
Q

where are leucoplasts found and their function

A

parenchyma cells of root, stem , seeds

they act as storage organelles

81
Q

leucoplasts are classified into

A

amyloplasts, elaioplast, proteinoplast

82
Q

what is the function of amyloplast, elaioplast, proteinoplast

A 
store 
starch 
lipids
proteins 
in repsective order
83
Q

what is the function of chromoplasts and their location

A

they synthesize coloured pigments other than green

they are present in colored parts of plants (flower petals /fruit walls)

84
Q

describe the structure of chloroplasts

A

discoid structure containing
outer membrane (contains porins -freely permeable to small molecules)
inter membrane space
inner membrane (semi-permeable and rich in protein)
stroma
thylakoid sheets

85
Q

describe the composition of stroa

A 
colorless proteinaceous substance
contain small circular DNA 
al kinds of RNA 
70S ribosomes 
enzymes 
thylakoids
86
Q

describe the internal structure of chloroplasts

A

small thylakoids (contain photosynthetic pigment) stack on top of each other (about 20-25)

large thylakoids/ intergrana (donot contain photosynthetic pigment and are colorless) connect the grana

there are almost 40-60 grana

87
Q

eukaryotic nucleus is composed of

A

nuclear envelope
nucleoplasm
nucleoli
chromatin

88
Q

describe the structure of nuclear envelope

A

double membrane separated by perinuclear space
composed of lipid bilayer and proteins
outer layer is covered with ribosomes and is continuous with RER
nuclear pores composed of nucleoporin are present

89
Q

what is the function of nuclear pores

A

regulate nucleo-cytoplasmic exchange of materials such as
smaller molecules diffuse through the pores
larger molecules are transported by cell signaling mechanisms and then diffused with the help of nucleoporin

90
Q

describe the composition of nucleoplasm

A

transparent semifluid ground substance made up of proteins, enzymes (DNA RNA polymerase) free nucleotide and some metal ions (Mg) for synthesis of DNA and RNA along with histone and non-histone proteins

91
Q

what is nucleolus and its composition and number

A

it is a non-membrane bound structure in nucleoplasm

it may be one or more

consists of peripheral granular area containing ribosomal sub-units

central fibrillar containing rRNA and rDNA (involved in the construction of ribosomes)

92
Q

what is chromatin

A

network to thin thread like structure made up of DNA nad proteins

93
Q

what is chromosomes and its structure

A

coiled and condensed chromatin fibres during cell division are called chromosomes

a chromosomes is formed by two chromatids attached to each other by centromere in thinner segment called primary constriction

94
Q 
describe the structure of centromere 
function of kinetochores
A

each centromere has a complex of kinetochores on opposite sides of constriction

each kinetochore forms the site of attachment for a single microtubule during cell division

95
Q

what is secondary constriction

A

some chromosomes have another point of union along the length of chromatids called secondary constrictor or nucleolar organizer which gives rise to nucleoli during interphase

96
Q

prokaryotic cells include

A

archaea, bacteria, cyanobacteria

97
Q

what are the difference between prokaryotic and eukaryotic cells

A

prokaryotic cell does not have membrane bound organelles or nucleus where E cell has both

Prokaryotic DNA is dispersed in cytoplasm whereas E cell has it in nucleus

P cells don’t have 80S ribosomes

cilia and flagella composition and structure varies

prokaryotic cells divide by binary fission while E cells divide by cell division

Biology MDCAT (4 decks)

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