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biology > Cell: the unit of life (last 5 pages) > Flashcards

Cell: the unit of life (last 5 pages) Flashcards

1
Q

are mitochondria visible under microscope?

A

unless specifically stained, they are not

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2
Q

number of mitochondria per cell

A

variable
depends on physiological activity of cells

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3
Q

shape and size?

A

considerable variability is observed

typically:
>sausage-shaped/cylindrical
>having a diameter of 0.2-1.0um(avg 0.5um)
>length 1- 4.1 um

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4
Q

what divides the lumen into two aqueous compartments and what are they called

A

outer and inner membrane

outer and inner compartment

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5
Q

innercompartment

A
  1. aka matrix
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6
Q

cristae function

A

increase surface area

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7
Q

the two membranes also have their

A

own specific enzymes

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8
Q

composition of matrix

A
  1. single circular dna molecule
  2. few rna molecules
  3. 70s ribosomes
  4. components required for protein synthesis
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9
Q

mitochondria divide by

A

fission

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10
Q

Plastids are found in

A

ALL plant cells and in euglenoids

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11
Q

are plastids seen under the microscope

A

easily observed as they’re large

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12
Q

how do plastids impart specific color to plants

A

have specific pigments

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13
Q

based on what are plastids classified into groups

A

type of pigments

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14
Q

classification of plastids

A
  1. chloroplasts
  2. chromoplasts
  3. leucoplasts—amyloplasts, elaioplasts and aleuroplasts
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15
Q

chloroplast
1. contain
2. responsible for

A

chlorophyll and carotenoid pigments

trap light engergy for photosynthesis

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16
Q

Chromoplasts:
1. pigments?
2. what color do they give to plants

A
  1. FAT SOLUBLE carotenoid pigments such as carotene, xanthophyll etc
  2. yellow, orange, red
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17
Q

Leucoplasts

A

colorless plastids

of varied shape and sizes

with stored nutrients

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18
Q

three types of leucoplasts and what do they store

A

amyloplasts—carbs eg potato

elaioplasts— oil and fats

aleuroplasts—proteins

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19
Q

majority of chloroplasts are found in which part of plant

A

mesophyll cells of leaves

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20
Q

shapes of chloroplasts

A

lense-shaped, oval, spherical, discoid or ribbon-like

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21
Q

dimensions of chloroplasts

A

variable length(5-10mm) and width(2-4mm)

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22
Q

no of chloroplasts

A

1 in chlamydomonas
20-40 per cell in mesophyll

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23
Q

inner membrane of chloroplasts is

A

relatively less permeable

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24
Q

stroma lamellae

A

flat membranous tubules connect thethylakoids of the different grana
aka intergranal thylakoids

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25
Q

membrane of thyllakoid enclose a space called

A

lumen

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26
Q

contents of stroma of chloroplast

A
  1. enzymes for synthesis of carbs, proteins
  2. small, double-stranded circular dna and
  3. ribosomes(70s)
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27
Q

chlorophyll pigments are present in

A

thyllakoid

28
Q

ribosomes are seen under which microscope

A

electron

29
Q

ribosomes first observed by

A

George Palade 1953

observed as dense particles

30
Q

ribosomes

A

1.composed of RNA
2. no membrane
3. both 70s and 80s are composed of 2 subunits

31
Q

S in 70s

A

sedimentation coefficient…indirectly a measure of density and size

32
Q

cytoskeleton

A

network of filamentous, proteinaceous strutures in cytoplasm

33
Q

cytoskeleton functins

A
  1. mechanical support
  2. motility
  3. maintenance of the shape of the cell
34
Q

compare cilia and flagella

A

similarity: hair-like outgrowths of cell membrane

differences
cilia:
1 small structures, work like oars
2 cause the movement of either the cell or surrounding fluid

flagella:
1. longer
2. responsible for cell movement

35
Q

flagella in prokaryotes vs eukaryotes

A

structurally different

36
Q

what did electron micrograph of cilium and flagellum show

A

they are covered with plasma membrane

their core -axoneme possess number of microtubules running parallel to long axis

37
Q

the axoneme

A
  1. usually has 9 pairs of doublets of radially arranged peripheral microtubules
  2. and a pair of centrally arranged microtubules
  3. central tubules connected by bridges and enclosed by a central sheath
  4. which is connected to one of the tubules of each peripherial doublet by a radial spoke-totally 9
  5. peripheral doublets are interconnected by linkers
38
Q

arrangement of axonemal microtubules aka

A

9+2 array

39
Q

both cilium and flagellum emerge from

A

centriole-like structures called basal bodies

40
Q

centriole is an organelle??!!

A

YESS

41
Q

Centriole contains

A

two cylindrical structures-centrioles

that lie perpendicular to eachother-wach has an org of a cartweel

42
Q

centrioles are surrounded by

A

amorphous pericentriolar materials

43
Q

centrioles: structure

A
  1. made up of nine evenly spaced peripheral fibrils of tubulin
  2. each peripheral fibril=triplet
  3. adjacent triplets are linked
  4. central part=proteinaceous = HUB
  5. hub is connected with tubules of peripher. triplets by radial spokes made of protein
44
Q

centrioles function

A
  1. basal bdy of cilia flagella
  2. form spindle fibres that give rise to spinde apparatus during cell division in animal cells
45
Q

nucleus: Robert Brown

A

described nucleus as a cell organelle

46
Q

nucleus: Fleming

A

named the material of the nucleus that stained by basic dyes as chromatin

47
Q

nucleoprotein fibres in interphase nucleus is described as

A

highly extended and elaborate

48
Q

nucleoproteins fibres

A

chromatin, nuclear matrix and one or more spherical nucleoli

49
Q

which microscope was used to study abt the nuclear envelope

A

electron

50
Q

space between the two parallel membranes of nuclear envelope

A

perinuclear space

51
Q

perinuclear space width

A

10 to 50 nm

52
Q

nuclear envelops forms a

A

barrier between materials inside nucleus and that of cytoplasm

53
Q

outer membrane of nucleus

A

continuous with ER

also bears ribosomes

54
Q

nuclear pores are formed by

A

fusion of the two nucclear membranes

55
Q

nuclear pores are used for

A

movement of RNA nd proteins betwn nucleus and cytoplasm

56
Q

nuclear matrix

A

aka nucleoplasm

contains nucleolus, chromatin

57
Q

nucleolus

A

content of nucleolus continuous with the rest of nucleoplasm

not a membrane bound structure

sit of active rRNA synthesis

larger=actively carrying out protein synthesis

58
Q

interphase nucleus vs other stages

A

interphase: nucleus has a loose and indistinct network of nucleoprotein fibres called chromatin

other: chromosomes instead of nucleus

59
Q

chromatin composition

A

DNA
histones
non-histone proteins
RNA

60
Q

length of dna in one hunam cell

A

2 metres in 46 chromosomes

61
Q

centromres

A

primary contriction

disc shape kinetochores on their sides

62
Q

4 types of chromosomes

A

metacentric: centromere at middle, equal arms of the chromosome

sub-metacentric: nearer to one end, one short and one longer

acrocentric: close to one end, one extremely short and one very long arm

telocentric: terminal centromere

63
Q

are secondary constrictions seen in all chromosomes?

A

no, just a few

64
Q

secondary constrictions

A

nonstaining
at constant location
gives the appearance of small fragment called satellite

65
Q

microbodies

A

many membrane bound minute vesicles

contain various enzymes

both in plants and animal cells

biology (4 decks)

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