cells

Question 1

Cell membrane

Answer 1

• Phospholipids are a major component of biological molecules.Due to the nature of phospholipids. The cell membranes made up of two layers of phospholipid- phospholipid bilayer
• besides the phospholipid bilayer, the cell membrane also contains various proteins, carbohydrate chains, and cholesterol attached to or embedded within the phospholipid bilayer

Question 2

Cell membrane ( fluid mosaic model)

Answer 2

• The fluid mosaic model is used to describe the structure of the cell membrane.
• the cell membrane is fluid in that phospholipids and proteins are not stationary but can move rapidly the across surface of the membrane
• the cell membrane is a mosaic in that many different protein molecules are randomly scattered and embedded throughout the phospholipid bilayer

Question 3

Nature of cell membrane

Answer 3

• Due to the nature of phospholipids, only small hydrophobic molecules can pass through the phospholipid bilayer. As such, for hydrophilic or water soluble molecules which are unable to pass through the cell membrane, transport proteins are required
• hence, the cell membrane is partially permeable, allowing only certain substances to pass through it. it functions to separate and protects a cell from its surrounding environment and controls how substances move in and out of the cell

Question 4

Stuff cytoplasm contains

Answer 4

• Cytosol: aqueous solution of essential ions, soluble proteins and soluble organic compounds such as sugars and amino acids
• cytoskeleton: network of protein fibers that give support, motility and regulation to the cell
• organelles: structures with specialized functions, suspended in cytosol

Question 5

Cytoplasmic streaming

Answer 5

Cytoplasmic streaming takes place in the cytoplasm of cells.it is the movement of the fluid substance (cytoplasm) within a plant or animal cell. Cytoplasmic streaming aids in the transport of materials and organelles around the cell.

Question 6

Nucleus structure

Answer 6

• Largest organelle within the eukaryotic cell, usually spherical
• consist of the nuclear envelope which separates nucleus from the cytoplasm
• contains nucleolus which synthesizes ribosomes
• contains DNA
• found on almost all eukaryotic cells except matured red blood cell

Question 7

Nucleus function

Answer 7

Contains the hereditary material (DNA) and controls the activities of the cell

Question 8

Rough endoplasmic reticulum structure

Answer 8

• A system of flattened membrane-bound sacs
• appears “rough” under electron microscope because of the presence of ribosomes on its surface

Question 9

Rough endoplasmic reticulum function

Answer 9

Protein synthesis. The polypeptide chain synthesized by the ribosomes will be folded in the RER

Question 10

Smooth endoplasmic reticulum structure

Answer 10

Consists of fine tubules

Question 11

Smooth endeplasmic reticulum function

Answer 11

• Lipid synthesis
• detoxification of drugs and poisons (liver)
• storage and release of calcium ions

Question 12

Golgi apparatus structure

Answer 12

Consist of stacks of flattened membrane-bound sacs

Question 13

Golgi apparatus function

Answer 13

Chemically modifies products receive from the ER and packages them, before sending them to destinations inside or out of the cell using vesicles

Question 14

Lysosomes structure

Answer 14

• Small, spherical vesicles surrounded by a single membrane
• Contain hydrolytic enzymes such as lipases, proteases, and nucleuses

Question 15

Lysosomes function

Answer 15

• To digest materials made in the cell or take in from outside by phagocytosis
• to digest worn-out organelles in the cell, a process known as autophagy

Question 16

Animal vacuoles structure

Answer 16

• Fluid-filled sac bound by a single membrane
• formed either by the pinching-off part of the cell membrane, or by enlargement of a vesicle from the Golgi apparatus
• Usually relatively smaller and exist temporarily

Question 17

Animal vacuoles function

Answer 17

Food vacuoles: formed by phagocytosis

Question 18

Plant vacuoles structure

Answer 18

• In mature plant cells, the large central vacuole is permanent and occupy over 80% of the cell volume
• enclosed by single, partially permeable membrane called the tonoplast
• filled with cell sap, a solution of dissolved such as sugars, ions, waste products and pigments

Question 19

Plant vacuoles function

Answer 19

• Storage of nutrients such as protein storage in seeds and inorganic ions
• disposal sites for metabolic by-products that would endanger the cell if they accumulated in the cytosol
• may contain pigments that color the cells

Question 20

Mitochondria structure

Answer 20

• Rod-shaped or cylindrical
• bounded by double membrane

Question 21

Mitochondria function

Answer 21

• Involved in aerobic respiration
• ATP is the “energy” molecule in living organisms
• abundant in metabolically active cells

Question 22

Chloroplasts structure

Answer 22

• Bounded by a double membrane
• contain chlorophyll
• Contain thylakoids and stroma

Question 23

Chloroplasts function

Answer 23

Site of photosynthesis

Question 24

Ribosomes structure

Answer 24

• Small, round structures found in all cells
• may occur as free ribosomes suspended in the cytosol or bound to the RER

Question 25

Ribosomes function

Answer 25

• Sites of polypeptide synthesis
• free ribosomes generally make proteins that will function within the cytosol
• bound ribosomes generally make proteins that are destined for insertion into membranes, for packaging within certain organelles such as lysosomes, or for export from the cell

Question 26

Centrioles structure

Answer 26

• Small, hollow cylinders that occur in pairs
• found in animal cells but absent in plant cells

Question 27

Centrioles function

Answer 27

Centrioles play a roll in cell division in animal cells

Question 28

Plant cell vs animal cell (cell wall)

Answer 28

Plant cell - surrounded by the cell wall in addition to the cell membrane
Animal cell - cell wall is absent, only surrounded by the cell membrane

Question 29

Plant cell vs animal cell (chloroplasts)

Answer 29

Plant cell- chloroplasts are present in large numbers in photosynthetic cells
Animal cell-absent

Question 30

Plant cell vs animal cell (centrioles)

Answer 30

Plant cell - absent
Animal cell - present

Question 31

Plant cell vs animal cell (vacuole)

Answer 31

Plant cell- present as a single, large and central vacuole
Animal cell- vacuoles are small and numerous