Cell as basic unit of life lesson 3 (2 webinars )): lectures 5 and 6

Question 1

what is the nucleolus?

Answer 1

dark structure inside nucleus .

Question 2

where are plastids present ?

Answer 2

bacteria and plant cells . in plats it is responsible for photosynthesis.

Question 3

is blue green algae eukaryotic or prokaryotic ?

Answer 3

it is prokaryotic

Question 4

what are some differences between animal and plant cells ?

Answer 4

Golgi body in plant cell is small and formed of many units while in animal cells its a complex single unit .

plant cells lack centrosomes and centriole ( which play an important role in cell division of animal cells .

Question 5

do fungi have a cell wall?

Answer 5

yes.

Question 6

what are the main structures of bacterial , plant , and fungi cell wall?

Answer 6

bacteria : peptidoglycan

fungi :chitin

plant : cellulose

Question 7

what is the cell membrane made out of ?

Answer 7

phospholipids , proteins , carbohydrates , and cholesterol (

Question 8

what are the ways molecules move across cell membrane ?

Answer 8

diffusion :molecules moving from high concentration to low concentration across the concentration gradient across the plasma membrane , without using any energy

osmosis: movement of water across semi permeable membrane from low solute concentration to high solute concentration .(according to concentration of solute )

active transport : if cell is larger and requires energy to move across plasma membrane

phagocytosis : cell eating ( solid molecules being engulfed by cell )

pinocytosis : cell drinking ( cell engulfing fluid )

exocytosis : cell secreting its product.

Question 9

who described the fluid mosaic model of the plasma membrane ?

Answer 9

singer and Nicolson (1974)

Question 10

discuss the fluid mosaic model .

Answer 10

plasma membrane is formed of phosphate bilayer. phosphate head will be pointing outwards and fatty acid tail will be pointing inwards .

the phosphate heads are not fixed , they can move , they are fluid.

proteins are embedded randomly as peripheral or integrated portion of bilayer

Question 11

which part of the phospholipid is hydrophilic and which are hydrophobic ?

Answer 11

phosphate heads are hydrophilic (polar structure )

fatty acid tail is hydrophobic

Question 12

drugs are made to be fatty/ lipid soluble.

Answer 12

..

Question 13

what does integrated and peripheral protein mean?

Answer 13

peripheral proteins are proteins only associated on the surface of the bilayer

integrated proteins are proteins that are across both the outer and inner layer of the bilayer

Question 14

what is the function of cholesterol in the bilayer ?

Answer 14

it stabilizes the cell membrane .

Question 15

WEBINAR 2->

Answer 15

FROM THIS POINT ONWARDS

Question 16

why is cystic fibrosis caused?

Answer 16

abnormalities of one abnormal protein in phospholipid bilayer that is responsible for chlorine transportation

Question 17

how does cystic fibrosis affect the teeth?

Answer 17

they look blue due to deposition of chlorine.

Question 18

what is the protoplasm ?

Answer 18

living substance in cell that contains all vital products including cytoplasm and nucleus

Question 19

what are the none living cell inclusions in cytoplasm ?

Answer 19

ergastic substance and cytoskeletal elements

Question 20

what’s the cytoplasm without cell organelles called?(only fluid)

Answer 20

cytosol

Question 21

what is the nucleus surrounded by?

Answer 21

double layered porous (structures can leave or enter nucleus through these pores)nuclear membrane

Question 22

what is the fluid inside the nucleolus called?

Answer 22

karyolymph (nucleoplasm )it contains chromatin and nucleolus

Question 23

what are the 2 parts of the karyolymph ?

Answer 23

structureless phase : nuclear sap that is made up of phospholipids , proteins , and enzymes

structural phase: is composed of chromatin network and nucleolus .

Question 24

when does the chromosome take on the X shape?

Answer 24

when cell is in resting state it contains a thread of line (or rod)called chromatin .when the cell is dividing , in metaphase it condenses and takes on the X shape because it now has 2 sister chromatids.

Question 25

what are the dark stained and light stained areas on the chromosome called?

Answer 25

the dark stained area is called heterochromatin . it is more condensed . it is inactive and doesn’t have a lot of genes .

the faint part is called euchromatin , it is less condensed and is genetically active

Question 26

what does chromatin contain ?

Answer 26

DNA , histone , and some RNA

Question 27

how many nucleoli does each nucleous contain ?

Answer 27

2-3

Question 28

what is responsible for forming the nucleolus ?

Answer 28

nuclear organizer chromosomes .They organize themselves in such a way that the RNA of the chromatin will be condensed together and visible as nucleolus .

*which is why the main function of the nucleolus is formation of RNA

Question 29

what is the main function of the nucleolus ?

Answer 29

synthesis of RNA