Cell Structure and Function Flashcards
1
Q
which types f organisms have cell walls
A
plants, prokaryotes and fungi
2
Q
why dont animal cells have cell walls
A
prob due to their locomotor mode of life
3
Q
plant cell walls are made up of
A
cellulose
4
Q
cell wallls of prokaryotes are made of
A
petidoglycan
5
Q
fungi cell wall is made
A
chitin
6
Q
the cell wall is ———— permeable
A
FULLY
7
Q
enlist the three layers of cell wall
A
PRIMARY CELL WALL
MIDDLE LAMELLA
secondary cell wall
8
Q
primary cell wall develops during
A
cell division in a newly growing cell
9
Q
describe the structural properties of primary cell wall
A
thin and flexibl
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
11
Q
which feature gives cell wall its stength
A
crisscorss arrrangemnt of microfibrils
12
Q
the primary cell wall is well adapted to ————
it stretches —————
A
growth
plastically (irreverably)
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
14
Q
generally which cells posses secondary cell wall
A
dead cells
15
Q
cell containing secondary cell wall are for which purpse
A
support
16
Q
when does secondary cell wall deveop
A
whwen the cell has reached max size
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
18
Q
what is the chemical composition of secondary cell wall
A
cellulose,hemicelluose, lignin, inorganic salts and waxes
19
Q
describe the structure of secondary cell wall
A
crisscros arrangement of microfibrils
lignin cements and anchors microfibrils together(responsible for ridgidness0
20
Q
what is the purpose of secondary cell wall
A
provides definite shape and support to cell
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
22
Q
what is middle lamella composed of
A
sticky ,
gel like magnesium and calcium salts
pectin
23
Q
plasma membrane is the boundary of —————-
A
protoplasm
24
Q
in whcih cells is plamsa membrane found
A
al living prokaryotic and eukaryotic cells
25
what is the composition of plasma membrane
60-80% proteins
20-40% lipids
and small quantity of carbohydrates
26
what is fluid mosaic model
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
27
what is the thickess of plasma membrane
7nm
28
describe the lipid bilayer of plasma membrane
phospholipids hydrophilic heads face the surface and hydrophilic tails face each other
steroids, cholesterol are wedged between phospholipids at intervals
29
internal and external surface of plamsa membrane is not
identical
30
-------------------- determines most of the functions of plasma membrane
proteins, glycoproteins, glycolipids
31
what supports the plasma membrane and where is it present
cytoskeleton which is attached to inner surface of plasma membrane
32
what are the functions of plasma membrane lipid
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
33
what is the function of proteins in cell membrane
may act as channel, carreir protein
enzyme
receptor
antigen
34
what is the function of glycolipids and glycoproteins in cell membran
as cell surface antigens
cell to cell recognition
cell to cell adhesion
35
transport occurs across the plasma membrane to
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
36
the living matter of cell is called
protoplasm
37
where and in which cells is cytoplasm present
in between plasma membrane and nucleus
| in eukaryotic and prokarytoic cells
38
describe the composition of cytoplasm
salts,sugar,amino acids fatty acids, nucleotides, vitamins and dissolved gases are in form of true solution
proteins, and large molecules form colloidal solutions
39
what is cytosol and its location
inner portion of cytoplasm towards the nucleus which is less viscus
40
what is cytogel and its location
peripheral portion of cytoplasm which is more viscous
41
what is cyclosis and its purpose
circular streaming movement in cytoplasm due to contractile activity of microfilaments
it is responsible for distribution of contents in cytoplasm
42
what are organelles
highly organized discrete structures specific for carious cellular functions generally enclosed in a membrane except for ribosomes
43
what is endoplasmic reticulum
an interconnecting network of cisternae (elongated closed sacs) which extend from nuclear membrane to plasma membrane throughout the cytoplasm of all eukaryotic cells
44
describe RER along with its function
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
describe smooth ER along with its functions
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
when was golgi apparatus discovered and by who
camillo golgi
| 1898
47
describe the structure of golgi body
stack of flattened membrane bound sacs (cisternae) together with system of associated vesicles (Golgi vesicles)
48
what is cis face of golgi body
forming face / convex face/ outer face
49
what is trans face
maturing face/ concave face/ innner face
50
what is the funtion of golgi body
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
how is phragmoplast formed and what is its function
during cytokinesis golgi vesicles arranged at equator fuse together to form it
new cell wall is derived from it
52
what are lysosomes and what does they contain
single membranous, spherical vesicles containing digestive and hydrolytic enzymes
53
how are lysosomes formed
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
what s primary lysosome
newly formed lysosomes before the start of their functions
55
what are secondary lysosomes
endosomes that fuse with primary lysosomes
56
what are endosomes, phagosomes, autophagosomes
vesciles formed by endocytosis
vesciles formed by phagocytosis
vesicles formed by autophay
57
what are the major functions of lysosomes
intracellular digestion
autophagy
autolysis
release of extra cellular enzyes
58
what is contractile vacuole
secondary lysosome containing waste products after digestive materials have been absorbed by cytoplasm
59
what is intracellular digestion
ingestion of food vacuole
fusion primary lysosome with food vacuole to form secondary lysosome
formation of contractile vacuole
exocytosis of undigested waste products
60
what is autophagy
process by which unwanted structure within cell are engulfed and digested within lysosomes
61
what is autolysis
cell death when a particular cell is required to be disintegrate
62
describe autolysis
lysosome burst their enzymatic contents disperse throughout the cell cytoplasm
cell disintegrates into fragments which are phagocytosed by other cells
63
what are lysosomal storage diseases
accumulation of various substances in the cell due to absence or lack of lysosomal enzymes
64
nature of lysosomal storage disease is
hereditary and congenital
65
how many lysosomal storage diseases have been indentified
20
66
what is one common example of lysosomal storage disease
lipid digesting enzymes is missing or inactive
| brain becomes impaired due to accumulation of lipids in cells
67
what are vacuoles
large vesicles originating from endoplasmic reticulum, gogli body and plasma membrane
68
what are the functions of vacules in organisms except plants
in animals food vacuoles are formed by phagocytosis
in fresh water protocists contactile vacules pump exess water out of cell
69
describe function and structure and development of vacuoles in plants
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
the number of mitochodira in a cell coorelates with
the cels level of metabolic activity
71
how are new mitochondria formed
self replicate by fission
72
describe the shape of mitochodria
they ae cylindrical or rod shaped
73
describe the structure of mitochondria
```
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
what is the function of porins in outer membrane of mitochondria
they allow free passage of various molecules into intermembrane space
75
describe the composition of mitochondrial matrix
```
jelly like material
contains circular DNA
all kinds of RNA
ribosomes (70S)
enzymes
```
76
where are plastids found
plant and algal cells
77
why are plastids essential
necessary for photosynthesis and food storage
78
plastids are classified into
proplastids, leucoplasts, chromoplasts and chloroplast
79
what are proplastids
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
where are leucoplasts found and their function
parenchyma cells of root, stem , seeds
| they act as storage organelles
81
leucoplasts are classified into
amyloplasts, elaioplast, proteinoplast
82
what is the function of amyloplast, elaioplast, proteinoplast
```
store
starch
lipids
proteins
in repsective order
```
83
what is the function of chromoplasts and their location
they synthesize coloured pigments other than green
| they are present in colored parts of plants (flower petals /fruit walls)
84
describe the structure of chloroplasts
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
describe the composition of stroa
```
colorless proteinaceous substance
contain small circular DNA
al kinds of RNA
70S ribosomes
enzymes
thylakoids
```
86
describe the internal structure of chloroplasts
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
eukaryotic nucleus is composed of
nuclear envelope
nucleoplasm
nucleoli
chromatin
88
describe the structure of nuclear envelope
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
what is the function of nuclear pores
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
describe the composition of nucleoplasm
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
what is nucleolus and its composition and number
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
what is chromatin
network to thin thread like structure made up of DNA nad proteins
93
what is chromosomes and its structure
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
```
describe the structure of centromere
function of kinetochores
```
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
what is secondary constriction
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
prokaryotic cells include
archaea, bacteria, cyanobacteria
97
what are the difference between prokaryotic and eukaryotic cells
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
