biology unit 1

cells

- all living things are composed of cells 

- new cells are formed only by the divison of pre-living cells 

- the cell contains inherited infomation (genes)

-metablic reactions take place within the cells

eukaryotic cells- plant and animal cells , they contain a nucleus membrane bound organelles.     

nucleus- contains cell DNA , control the cell.

plasma membrane- protects cell from  

 nucleolus- dense DNA and protien, makes ribosomes

vesicle- small membrane boundedsac, transports and stores substances in the cell

lysommes-destroys old organelles and pathogens

 centroles- make spindle in cell division  

cytoplasm- fluid that fills the cell, site of metablioc reactions     

mitochondria- surrounded by a double membrane, site of respiration                                    

 gogli appuratus- enclosed by a membrane- modifies protiens and packages them in vesciles for transport  

80's ribsomes- site of protien synthisis

 Smooth ER- lipids made here rough ER- protiens made here

cell wall- protects and supprts the cell

chloroplast- site of photosynthesis,  trapped by chlorophyll used to produce carbohydrate molecules from water and carbondioxide.

vacuole- contains cell sp, maintains turgor to ensure rigid frame work in the cell  

tonoplast- allow molecules to pass through

amyloplast- responsable for synthisis and storage of starch.

plasmodesta- enable transport and communication between individual parts of the cell

pits- allow water to enter the xlyem vessels

prokaryotic cells- singled cell, bacterail, have no nucleus

cell wall- prokaryotic cells are surrounded by a cell wall, made of peptigoglycen, protects the cell  

capsule- protects the cell  it enhances the ability of bacteria to cause disease

ribsomes- used for protien synthisis 

nucleoid- genetic infomation can be found

plasmid- carrys genes that may benift the survival of the organism

positive-

-purple stain when absorbing

- gram + bacteria present

Negative-

-smear stained pink

-gram - bacteria present

- because there thinner cell walls & lipid membranes, allow ethonal to wash off the crystal violet purple stain

sperm cell-

-male gamete in animals

- tail like structure - stream lined so can move fast to the egg

- many mitochondira- supply energy needed for movemnet to egg

-head made of digestive enzymes- realesed when the sperm meets the egg to digest the protective layer and allow the sperm to penatrate

FUNCTION- deliver genetic info to egg

egg cell

-female gametes in animals

- nucleus- houses genetic infomation

-zona pellucida- outer protective layer, reduce chnaces of spem meeting the egg

FUNCTION- supply protiens needed by the fertalised egg

red blood cells

- biconcave shape- increases the surface area: volume ratio of the erythrocytes

- flexible- so they can squeeze through narrow blood capilaries

-contain large quantities of protiens called haemaglobin, witch can bind oxygen

-dont have a nucleus so there is more room for haemaglobin

FUNCTION- to transport oxygen around the body

white blood cells

- play important part of the immune system

- invovled in destroying pathogens and digesting them ( breaking them down)

- they have multi lobed nuclei, which enables them to squeeze through small gaps when traveling to the site of infection

FUNCTION- invovled in destroying pathogens

palisade mesophyll cell 

- type of plant cell

- found in the leaves, rectangualr boxed shaped cells that contain chloroplasts

-chlorosplast are used to absorb a large amount of light for photosynthisis

- move around the cytoplasm in order to maximise the amount of light absorbed

root hair cell

- type of plant cell

- found at the plant roots near the growing tip

- they have long hair called root hair, the root hairs increase  the surface area of the cell to maximise the movemnt of water & minerals from the soil into the plant root

FUNCTION- to collect water and mineral nutrients that are present in the plant 

 squamous epithelial

location- line organs and surfaces

function- one cell thick, form thin layers , ideal for rapid diffusion. eg the alveoli in the lungs, rapid diffusion of oxygen

damaged caused by smoking-  

- irritates, causes inflamation and scaring

-alveloi walls become thicker due to scaring 

- the damge to air sacs causes  emphysema 

- lungs loose there natural elastcity

columar epithelial

location- line the trachea in the  respiratory system, column shaped cillated cells with hair like structures called celia covering the exposed cell surface

function- protect the lungs from infection by sweeping away pathogens and secreting mucus to help trap pathogens

how the lungs are protected-  

- they secret mucus to help trap any unwanted particles that are present in the air that we breathe

- prevents bacteria reaching alveoli

endothelial tissue

location- lining of the heart, blood vessels & lymthetic vessels

function- provide a short cell difusion pathway for the movement of varoius substances eg digestion into the blood stream- blood plasma & tissue in and out of the blood capilairies

how arteriosclerosis develops- carbon monxide and high BP can damage  and encorage the growth of the smooth muscles and the deposition of fatty substances

respiritory diseases-ones of the biggest causes of death world wide, chronic obstructive pulmonary dissorder COPD is a term for a group of diseases that cause a reduction in airflow in the lungs and are not fully reversable

emphysema- a type of COPD the gradual break down of the alveolar walls and damage to bronchiolies and alveolar walls, effects smoking as the smoke parylises cilia and changes the muscus secretion , smoker has to cough more to clear the lungs

structure of neurones

dentrite- branch like structures extending away from the cell body, there job is to recieve messages to travel to the cell body

axon- tube like structure that carries and electrical implulse from the cell body to the structues at the oppsoite end of the neuron

synapse- chemical junction between the axon terminals of one neuron and the dendrites of the next

neuron- allow to transmit signals in the form of electric impluses from the brain to the body and back 

myelin sheath- fatty material that wraps around the axon, functions as insulation to minimize dissipation of the elctrical siganl as it travels down the axon

Sensory receptors-These detect the changes in the environment (stimulus)

Sensory neurons-Nerve cells that send a signal from the sensory receptors to the CNS

Motor neurons-Nerve cells that receive a signal from the CNS and transfer it to the effector

resting potential-Resting potential is the term given to a neuron that is not transmitting an action potential and is at rest.

action potential-Fast twitch oxidative muscle fibres are similar in structure to slow twitch muscle fibres. They contain many mitochondria, myoglobin and blood capillaries, but they are able to hydrolyse ATP much more quickly and therefore contract quickly. They are relatively resistant to fatigue.

1. Na+ channels open, Na+ begins to enter the cell

2.K+ channels open K+ begins to leave cell

3. na+ channels become refractory, no more na+ enter the cell

4. K+ continues to leave cell, causes membrane potential to return to resting level

5. k+ channels close, na+ channels reset 

6. extra k+ outside diffuses away 

Synapses

 When the nerve impulse reaches the end of the neuron, it must cross a gap called a synapse to get to the next neuron or the effector cell.

 A nerve impulse crosses the synapse in the form of a chemical trans- mitter called a neurotransmitter.

 Neurotransmitters diffuse across the synapse and initiate an action potential in the neuron at the other side. The presynaptic neuron ends in a swelling called the synaptic bulb and it contains many mito- chondria as ATP is needed.

 The neurotransmitters are stored in temporary vesicles in the synap- tic bulb that can fuse with the surface to release the neurotrans- mitters into the synapse.

 They also contain voltage-gated calcium ion channels

-Skeletal muscle is found attached to bones. You can control its contraction and relaxation, and it sometimes contracts in response to reflexes.

- Cardiac muscle is found only in the heart. It contracts at a steady rate to make the heartbeat. It is not under voluntary control.

 - Smooth muscle is found in the walls of hollow organs, such as the stomach and bladder. It is also not under voluntary control.

slow twitch

Slow twitch muscles are more effective at using oxygen to generate energy in the form of ATP, for continuous and ex- tended muscle contractions over a long time. These fibres help marathon runners and endurance cyclists to continue for hours. Slow twitch fibres have:less sarcoplasmic,  reticulum, more mitochondria for sustained contraction, more myoglobin, a dense capillary network, these fibres release ATP slowly by aerobic respiration. long distance runner

fast twitch

Fast twitch oxidative muscle fibres are similar in structure to slow twitch muscle fibres. They contain many mitochondria, myoglobin and blood capillaries, but they are able to hydro- lyse ATP much more quickly and therefore contract quickly. They are relatively resistant to fatigue. 800 m sprinter

Fast twitch glycolytic muscle fibres have relatively less myo- globin, few mitochondria and few capillaries. They contain a large concentration of glycogen that provides fuel for anaero- bic respiration. They contract rapidly but also fatigue.  100m sprinter