Cell: The unit of life

Question 1

Cell theory

Answer 1

Mathis Schleiden and Theodore Schwann

modified hypothesis by Rudolf Virchow: new cells are formed from pre-existing cells

Question 2

Cell envelop and its modifications

Answer 2

i. Glycocalyx: sticky character; helps in resisting phagocytosis; can be loose mucilaginous sheath - slime layer or thick capsule
ii. Cell wall: made up of peptidoglycan or murein
iii. Plasma membrane: Innermost layer; semipermeable

Question 3

Mesosomes

Answer 3

In the form of vesicles or tubules and lamellae; equal to mitochondria in eukaryotes, as they participate in cellular respiration

Question 4

Inclusion bodies

Answer 4

Non-living; lie free in the cytoplasm - cyanphycean granules; or maybe covered in non-protein membrane - gas vacuoles

Question 5

Endoplasmic reticulum

Answer 5

• Provides support to the colloidal cytoplasm
• Rapid intercellular transport
• Variety of enzymes

Question 6

Golgi apparatus

Answer 6

Cis face (forming face): Recieving secretory material through transitional vesicles
Trans face (maturing face): responsible for releasing material secreted by cis face

Question 7

Golgi apparatus - functions

Answer 7

• Formation of lysosomes
• Packaging materials
• imp. site for formation of glycoproteins and glycolipids
• Formation of complex CHOs other than glycogen and starch
• Formation of cell wall

Question 8

Lysosomes

Answer 8

• intra and extracellular digestion
• fuctioning in cell division
  suicidal bags due to presence of hydrolytic enzymes

Question 9

Vacuoles

Answer 9

Bound by single membrane structure called tonoplast; facilitates transport ions against conc. gradient; conc. of material is higher in the vacuole

Question 10

Types of vacuoles

Answer 10

Contractile vacuole: osmoregulation and excretion; eg: amoeba
Food vacuole: Occur mainly in protists Engulfing food particles; fusion of lysosome and phagosome

Question 11

Mitochondria

Answer 11

Inner membrane is semipermeable to metabolites

matrix possesses single circular DNA few RNA, ribosomes(70s) and the components required for the synthesis of proteins

Question 12

Functions of mitochondria

Answer 12

• provides intermediates for synthesis of several biochemicals
• inner chamber has enzyme for synthesis of fatty acid
• helps in regulation of cellular metabolism
• apoptosis (programmed cell death)

Question 13

Plastid

Answer 13

Semi-autonomous; double membrane
found in all plant cells and euglenoids except few protistans
Types:
- leucoplasts
- chromoplasts: yellow-reddish in appearance; presence of fat soluble carotene
- chloroplasts: chlorophyll-containing or carotenoid pigments; trapping light energy

Question 14

Leucoplasts

Answer 14

Colourless

• amyloplasts: carbohydrate-containing
• elaioplasts: stores oils and fats
• Aleuroplasts: protein storing

Question 15

Functions of plastids

Answer 15

• Photosynthesis
• Consumption of CO2 and release of O2
• as chromoplast in order to provide colour to flower or fruits
• storing fats and lipids
• transduction of energy

Question 16

Chromatin

Answer 16

Part of the nucleus

euchromatin: lightly stained
heterochromatin: darkly stained