Topic 1

Question 1

list in order from smallest to largest the levels of organisation

Answer 1

chemical/molecular level
cellular level
tissue level
organ level
organ system level
the organism level

Question 2

define the molecular level

Answer 2

contains atoms (smallest unit of matter), molecules such as ions, proteins, carbs, lipids and nucleic acids.

function - structure/function, storage, messengers, control

Question 3

define the cellular level

Answer 3

a group of atoms, molecules and organelles working together, forms the basic unit of life.

Question 4

define the tissue level

Answer 4

a group of similar cells working together

4 main types of tissue - epithelial, connective, muscle and neural.

Question 5

define the organ level

Answer 5

made up of different tissues

(organ is a group of tissues)

organ functions are supplied by the tissues, there are multitasking tissues and specialist organs.

Question 6

define organ system level

Answer 6

an organ system is a group of organs working together.

humans have 11 organs with various functions

Question 7

define the organism level

Answer 7

all the organ systems working together to form a functional organism.

Question 8

define a cell

Answer 8

the basic unit of life, structural and functional unit of the body.

they can undertake metabolic reactions, maintain homeostasis, reproduce themselves and communicate

Question 9

what are the three main parts of a cells construction

Answer 9

1. plasma membrane
2. cytosol
3. nucleus

Question 10

describe the structure of the phospholipid bilayer

Answer 10

lipid bilayer

• phospholipids 70%
• cholesterol 20%
• glycolipids 5%

two phospholipids layers with fatty acid tails in the center (hydrophobic tails) and hydrophilic heads.

it is flexible/fluid - the fluid mosaic membrane is a constantly moving sea of lipids with a mosaic of proteins - lipids and many proteins can rotate and move sideways in their half so it is not rigid.

Question 11

what does flexibility depend on the membrane?

Answer 11

depends on two things:

• number of double bonds in fatty acid tails and cholesterol.

more double bonds = more flexible
more cholesterol at body temp = less flexible
more cholesterol at low temp = increases fluidity.

Question 12

why is it important for the membrane to be flexible?

Answer 12

a flexible membrane allows self-sealing if it penetrated, allows movement during cell division and secretion of substances (helps to import and export substances if needed).

Question 13

what are the functions of the cell membrane

Answer 13

1. acts as a barrier separating inside and outside.
2. controls the flow of substances into and out of the cell.
3. helps identify the cell to other cells such as immune cells.
4. participates in intercellular signaling.

Question 14

list all the cellular organelles

Answer 14

nucleus 
ribosomes
endoplastic reticulum - rough and smooth
golgi apparatus 
mitochondria 
chloroplast
vacuole 
centriole 
centromere
cytoskeleton 
lysosome 
flagellum 
cilia, microvilli and flagella 
peroxisomes
proteasomes

Question 15

what is the cytoplasm

Answer 15

contains the cytosol and other organelles

where most cellular activities occur such as metabolic pathways including glycolysis and processes such as cell division.

Question 16

what are organelles

Answer 16

small individual structures within the cytoplasm that have various functions

Question 17

what is the difference between membrane bound organelles and non membrane organelles

Answer 17

organelles without membranes have more functioning with structural support or moving substances within cells but membrane bound organelles allow specialised functions to be performed within them,

Question 18

what is the cytoskeleton

Answer 18

is a network of three filaments types (proteins) in cytosol.

it helps maintain cell and organelle shape and structure, generate movement.

functions as a scaffold that helps determine a cells shape and organise the cellular contents and aids movements of organelles within the cell, of chromosomes during cell division and of whole cell such as phagocytes.

Question 19

describe the three types of filaments

Answer 19

microfilaments - thinnest, actin, myosin, help generate movements.
e.g. white blood cells moving into tissue.

intermediate filaments - intermediate size, made of several proteins, very strong, stabilise organelle position, found where cell subjected to stress.

microtubules - largest (tubulin) grow from centrioles, move organelles and secretory vesicles and chromosomes.

Question 20

what are centromeres

Answer 20

located near the nucleus, it consists of a pair of centrioles and pericentriolar material.

function - the pericentriolar material of centrosome contains tubulins that build microtubules in nondividing cells.

that pericentriolar material of the centrosome forms the mitotic spindle during cell division.

peri = around

Question 21

what are cilia, flagella and microvilli

Answer 21

are extensions of the cell membrane that are supported by the cytoplasm

cilia - short hair like projections, extend from cells surface: beat in a coordinated manner in order to sweep away substances. appear in clusters.

flagella - long projections that propel an entire cell; only in sperm

microvilli - finger like projections from the cell membrane, greatly increase surface area of a cell.

Question 22

what are ribosomes

Answer 22

composed of rRNA and proteins in large and small subunits, made in nucleus; join together in cytosol.

site of proteins production

ribosomes on rough endoplasmic reticulum (RER) make proteins for the cell membrane or secretion out of the cell.

Question 23

what is the endoplasmic reticulum

Answer 23

flat, folded, membranous sacs attached to nuclear membrane.

two types:

• rough
• smooth

Question 24

what is RER

Answer 24

continuous with nuclear membrane, has ribosomes attached, synthesizes membrane protein, secretory proteins and organelle proteins that are transferred into organelles, inserted into the plasma membrane or secreted during exocytosis.

Question 25

what is the SER

Answer 25

extended from RER, synthesises fatty acids and steroid hormones, detoxifiers lipid soluble drugs.

the sarcoplasmic reticulum is a type of smooth endoplasmic reticulum in muscle, stores calcium ions needed for muscle contraction to occur (when muscles needs to be relaxed, Ca ions are stored).

Question 26

what is the golgi complex

Answer 26

modifies, sorts, packages and transports proteins received from rough ER.

forms secretory vesicle that discharge processed proteins via exocytosis into extracellular fluid, forms membrane, forms transport vesicle that carry molecules to other organelles, such as lysosomes.

Question 27

what are lysososmes

Answer 27

Vesicle containing digestive and hydrolytic enzymes (pH 5)

Reasonably acidic because enzymes are breaking substances that have been brought into cell.

Function:

Digest substances that enter a cell via endocytosis and transport final products of digestion into cytosol.

Carry out autophagy, the digestion of worn out organelles.

Implement autolysis, the digestion of an entire cell.

Accomplish extracellular digestion.

Sperm lysosomal enzymes digest their acrosome (protective cap) for fertilisation to occur.

Question 28

what are peroxisomes

Answer 28

Small vesicles containing enzymes to break down toxic molecules formed during metabolism or ingestion. Eg; alcohol, hydrogen peroxide, (H2O2), superoxide.

Don’t have the digestive enzymes that lysosomes do.

Question 29

what are proteasomes

Answer 29

Tiny stack of four protein rings around a central core containing proteases (protein digesting enzyme).

Destroy unneeded or faulty proteins in biochemical pathways after they have performed their function.

Break proteins into peptides, other enzymes break peptides into amino acids (recycles into new proteins).

Question 30

what is the mitochondria

Answer 30

Generates ATP through reactions of aerobic cellular respiration.

Play an important early role in apoptosis.

Question 31

what is the nucelus

Answer 31

Largest organelle surrounded by a nuclear (double) membrane with pores.

Most cells have one nucleus. Red cells have none; skeletal muscle cells have multiple.

Command and control centre of cell:

Controls cell structure, directs cell activities, produces ribosomes in nucleoli.

Contains DNA in 23 pairs of chromosomes. Genes code for a specific protein or enzyme.

Function:

Controls cellular structure

Directs cellular function

Produces ribosomes in nucleoli.

Question 32

explain cell ageing

Answer 32

As cell structure and function change, homeostatic responses decline – body more vulnerable to disease, infection, environmental stressors.

Some body cell types nerve divide. Eg; skeletal and cardiac muscle cells, most neurons or have limited capacity to undertake mitosis.

Outcome of both: damaged cells will not/ may not be replaced – reduction in function of tissue/organ.

“Ageing genes” (normal genes important for cell function) reduce in activity as we age – slows down vital cell processes.

Telomeres: protective DNA “cap” on chromosomes ends; typically get shorter each cell division.

High stress level – shorter telomere length.

Glucose – added randomly to proteins which causes irreversible cross linking of adjacent proteins – loss of elasticity – stiffness in tissues.

Increased autoimmunity – as membrane protein changes increase, cell identity markers may be affected. Altered cell identity markers eg MHC proteins may – antibodies which bind to the membrane – cell destruction. As protein changes to increase, autoimmune response increase – loss of tissue and reduction in function.