The cell

Question 1

What is the plasma membrane and what is its function?

Answer 1

-forms a cell’s flexible outer surface, separating the cells internal and external environment
-it regulates the flow of materials into and out of a cell to maintain the appropriate environment for normal cellular activities
-also plays a key roll in communication among cells and between cells and the external environment

Question 2

What is the structure of the plasma membrane?

Answer 2

-phospholipid bilayer made up of phospholipids, cholesterol and glycolipids

Question 3

What is the function of integral and peripheral proteins within the plasma membrane?

Answer 3

-integral proteins extend through both layers and allow small water soluble materials to cross the membrane
-peripheral proteins are loosely attached to the surface of the membrane and have roles in cell signalling and communication

Question 4

Describe the permeability of the plasma membrane

Answer 4

-selectively permeable
-allows some substances to move into and out of the cell but restricts the passage of others

Question 5

What is the phospholipid bilayer permeable to? Give examples

Answer 5

-is permeable to water and non polar (lipid soluble) molecules e.g fatty acids, oxygen, carbon dioxide

Question 6

What is the phospholipid bilayer non permeable to? Give examples

Answer 6

-isnt permeable to ions and large uncharged polar molecules e.g glucose and amino acids,
-proteins are able to be passed through using protein channels

Question 7

What are the 8 types of body fluids?

Answer 7

-intracellular fluid- fluid in body cells
-extracellular fluid- fluid outside cells
-interstitial fluid- between cells in tissues
-blood plasma- in blood vessels
-lymph- in lymphatic vessels
-cerebrospinal fluid- surrounds brain and spinal cord
-solute- any material dissolved in a fluid
-solvent- fluid that dissolves materials

Question 8

What is a passive process of transport?

Answer 8

-substance moves down its concentration gradient through the membrane, using only its own energy of motion
-includes simple diffusion and osmosis

Question 9

What is an active process of transport?

Answer 9

-ATP is required to move the substance against its concentration gradient
-e.g active transport

Question 10

Define the term diffusion

Answer 10

A passive process in which a substance moves due to its kinetic energy from an area of high concentration to an area of low concentration

Question 11

What is the difference between simple diffusion and facilitated diffusion?

Answer 11

-simple diffusion substances diffuse through the bilayer on their own e.g fatty acids, steroids, oxygen, carbon dioxide
-facilitated diffusion uses an integral membrane protein to assist a specific substance moving through the membrane e.g a membrane channel or carrier

Question 12

Define the term osmosis

Answer 12

A passive process in which there is a net movement of water through a selectively permeable membrane from an area of high water potential to low water potential

Question 13

What is an isotonic solution?

Answer 13

When the concentrations of two solutes are the same so cells maintain their normal shape

Question 14

What is a hypotonic solution?

Answer 14

a solution that has a lower concentration of solutes and a higher water potential

Question 15

What is a hypertonic solution?

Answer 15

A solution that has a higher concentration of solutes and a lower water water potential

Question 16

Define the term active transport

Answer 16

An active process in which cellular energy is used to transport substances across the membrane against its concentration gradient using energy from ATP

Question 17

What is a vesicle and what is its function?

Answer 17

-A small round sac formed by budding off from an existing membrane
-they transport substances from one structure to another within cells, and carry out endocytosis (materials move into a cell) and exocytosis (materials move out of a cell)

Question 18

What is a cell’s cytoplasm made up from?

Answer 18

-cytosol (the liquid portion of the cytoplasm)
-the cytoskeleton which provides a structural framework for the cell and generates movement. it is composed of microfilaments and microtubules

Question 19

What is the organelle centrosome and what is its function?

Answer 19

-found in pairs at a 90 degree angle to one another, it organises and grows the mitotic spindle which plays a key role in cell division

Question 20

What is the function of ribosomes?

Answer 20

The site of protein synthesis

Question 21

What is the function of the endoplasmic reticulum and what is the difference between the rough and smooth ER in appearance and function

Answer 21

-a network of folded membranes of flattened tubules
-Rough ER extends from nuclear envelope and has ribosomes on its outer surface, synthesises proteins
-Smooth ER extends from rough ER and has no ribosomes, synthesises lipids

Question 22

What is the function of the Golgi apparatus?

Answer 22

-to modify and package proteins

Question 23

What are lysosomes?

Answer 23

-Membrane-enclosed vesicles that contain digestive enzymes

Question 24

What are peroxisomes?

Answer 24

Contain several oxidases, which are enzymes that can oxidase various organic substances

Question 25

What are proteasome?

Answer 25

Continuously destroy unneeded, damaged, or faulty proteins

Question 26

What is the function and structure of the mitochondria?

Answer 26

-The site of respiration to produce ATP
-a series of inner folds called the cristae and a large central fluid-filled cavity

Question 27

Describe the structures of the nucleus

Answer 27

-Nuclear envelope separates the nucleus and cytoplasm
-nuclear pores pierce the envelope and control the movement of substances between the nucleus and the cytoplasm
-nucleoli are clusters of protein, DNA, RNA and are the sites of assembly of ribosomes
-genes control cellular structure and direct cellular activities
-the genes are arranged along chemical chromosomes

Question 28

Describe the process of protein synthesis

Answer 28

-DNA gene is transcribed to from RNA
-RNA attached to a ribosome where information in the RNA is translated into specific amino acids to from a new protein molecule

Question 29

Describe the process of transcription

Answer 29

-genetic information in DNA base is copied into a complementary sequence of codons in a strand of RNA
-transcription is catalysed by the enzyme RNA polymerase
-mRNA, rRNA, and tRNA are made

Question 30

Describe the process of translation

Answer 30

-when mRNA attaches to a ribosome and a protein is made by converting the sequence of nucleotides in mRNA into a specific sequence of amino acids

Question 31

What is meiosis?

Answer 31

-reproductive cell division that produces gametes (sperm and oocytes)

Question 32

What is mitosis?

Answer 32

-somatic cell division in which a body cell divides into 2 genetically identical daughter cells

Question 33

What is the somatic cell cycle composed of and what happens in each stage of the cycle (including mitosis)

Answer 33

-in interphase the cell replicates its DNA
-in mitosis is where the nucleus and cytoplasm divides to form 2 identical cells through the stages of prophase, metaphase, anaphase, telophase

Question 34

What is gerontology?

Answer 34

the scientific study of the process and problems associated with aging