sem 1 exam Flashcards
how scientists investigate
literature review: reviewing past discoveries
observation: information gathered using senses and instruments that enhance senses
classifying: placing things in group because of similarities in characteristics
experimentation: designed to support or disprove a hypothesis
steps to scientific method
- recognise a problem and make question
- collect info regarding to problem
- make hypothesis
- test hypothesis using experiment
- collect data
- draw conclusion on whether hypothesis was proved or disproved
if it was disproved, make new hypothesis
if new question arise from conclusions, then begin whole procedure again
ethical considerations
safety: should be risk fro participants and investigators
ethics: a set of moral principles held by majority
- voluntary participation
- informed consent
- no risk of harm
- Confidentially
- anonymity
cell membrane
outer boundary of cell, made up of a double layer of lips (phospholipid bi layer)
separates the cell from neighbouring cells and external environment. Determines which substances get into or out of the cell
cytoplasm
within the cell membrane. Thick fluid within cell membrane and all structures suspended in it it is more jelly like than cytoskeleton.
cytoplasm is responsible for giving a cell its shape. It helps to fill out the cell and keeps organelles in their place
cytosol: liquid part of cytoplasm, 75-90% water with dissolved substances. salts and. carbohydrates are dissolved, but proteins and fats don’t dissolve (suspended)
nucleus
Central region of the cell. Separated from cytoplasm by a nuclear membrane. DNA and nucleolus are suspended in nuclearplasm.
contains genetic information, 23 pairs of chromosomes. Nuclear membrane has gaps known as pores which large molecules can pass through. Nucleolus makes ribosomal RNA which makes ribosomes
ribosomes
free inside cytoplasm or bonded to endoplasmic reticulum. Very large spherical organelles found in all living cells.
Amino acids are joined together at the ribosomes to make proteins, does RNA translation. Found on their own in cytoplasm or attached to endoplasmic reticulum
endoplasmic reticulum
attached to the nucleus. Pairs of parallel membranes extending through cytoplasm and connecting cell membrane to nuclear membrane, some have ribosomes attached. Provides the surface in which chemical reactions can occur. Channels between paired membranes are used for storage or transport of materials. Rough ER is where proteins are made
Golgi body
free in cytoplasm. Flattened membrane bag stacked on top of each other. They modify proteins and package them in vesicles for secretion from the cell. Vesicles are pinched off from the edges of membranes.
at the edges of glory body membrane are small bubbles of liquids that contain proteins. bubbles surrounded by membrane and called vesicles
lysosomes
small spheres that contain digestive enzymes able to break down large molecules. They break down proteins and other materials that are taken into the cell or breakdown worn out organelles. If it explodes, enzymes spread out and cell dies. materials taken into cell in vesicles, lysosomes join with vesicle and and enzymes break down materials in it.
formed from the Golgi body
mitochondria
spiracle elongated structures spread through cytoplasm. Have a double membrane and its own DNA. Folded membrane inside a membrane. larger SA
release energy for the cell through the process of respiration. Powerhouse of the cell, provide energy in the form of ATP
centrioles
near the nucleus. Pair of cylindrical structures perpendicular to each other.
involved in the reproduction of the cell they form spindle fibres
cilia/flagella
on the surface of the cell. Tiny hairs called cilia, if it is longer and fewer it is called flagella
they move mucus and trapped particles (cilia in windpipe)
flagella in sperm cell helps it swim
cytoskeleton
free in cytoplasm along the cell membrane
they are a framework of protein fibres that give the cell its shape and assists in cell movement. Made of microtubules and microfilaments
microtubule: keep organelles in place and/or move them around the cell.
microfilaments: moves materials in cytoplasm and the whole cell
act as railway tracks guiding organelle or molecules to particular places. not permanent structure as it can built up and broken down as needed by the cell.
why are cells small
there is a limit to how big a cell can be.
A small cell will have a larger surface area to volume ratio then a large cell.
cells have to be microscopic to function effectively.
A large cell could not support itself because it would not have enough surface to absorb the nutrients required, and remove the wastes produced by its large volume
homeostasis
The maintenance of a constant internal environment of cells despite fluctuations in external environment
body systems work together to ensure a constant body temperature, correct level of molecules or ions maintained, fluid levels and body are correct
functions of cell membrane
- it is a physical barrier: protect ourselves and separate cells cytoplasm from the extra cellular fluid. this is important because the composition of the cytoplasm and the extracellular fluid are very different
- regulates passage of materials: what enters and leaves, controls the movement of materials into and out of the cell. Achieves this through its semipermeable membrane
- sensitivity: protein receptors in membrane are sensitive to certain or particular molecules around it for example hormones. The cell membrane is the first part of the sale affected by any changes in the extracellular fluid
- support: inside part of membrane has microfilament’s attached, which is part of the cytoskeleton. there are also connections between the membranes of adjacent cells that give support to the whole tissue of which the cells are apart
cell membrane structure
membrane is the phospholipid bilayer (2 layers), The main building blocks are phospholipids.
1. hydrophilic head made of an alcohol and glycerol group
2. hydrophobic tail made of chains of fatty acids
3. glycerol backbone
phospholipids can move sideways and allow water and other nonpolar molecules to pass through into or out of the cell
proteins and other molecules are in bedded in the membrane, it is called the fluid mosaic model.
fluid= proteins/molecules are constantly changing positions
mosaic=composed of many different types of molecules
A variety of proteins and cholesterol molecules are embedded in the bilayer some past through the membrane others are only on the surface. Cholesterol makes the membrane more fluid.
membrane proteins
- channel proteins: form a central pole, allow small ions, water, and other small molecules to pass through by simple diffusion
- receptor proteins: receive information to provide a response (hormone, insulin)
- Carrier protein: are specific, allow certain materials to bind to it, For example only glucose, amino acids. allows facilitated diffusion for example glucose and active transport (specific membrane pumps)
- cell identity markers: identifies the sale as self to prevent attack by the bodies immune system. They have carbohydrate parts attached to it to help cells in recognising each other and certain molecules
membrane transport methods
- diffusion and osmosis
- Carrier mediated transport: facilitated diffusion (passive), active transport (active)
- vesicular transport: endo/exocytosis
diffusion
occurs in gases and liquids
movement of molecules from areas of High concentration to low concentration, until evenly distributed. Because cell membrane is fatty, so most water soluble substances cannot diffuse through it except for oxygen and carbon dioxide
factors:
1. Concentration gradient: concentration and distance
2. surface area: larger surface area creates a larger rate of diffusion
3. barriers: thicker barriers slow diffusion rates, pores in a barrier in enhance diffusion
4. temperature: higher temperature leads to higher diffusion rates because particles have more energy
bring in water, oxygen, carbon dioxide, alcohol, fatty acids, ions, lipids, soluble drugs
fat soluble substances diffuse through lipid part of membrane
molecules within cells move with diffusion
concentration gradient
when the concentration of a substance is different at two places: the substance will diffuse along the concentration gradient until the concentration of the two areas become equal
x axis= distance
y axis= concentration
greater the difference in concentration, the steeper the gradient and the faster diffusion occurs
osmosis
diffusion of water across a semipermeable membrane. What are molecules move from high concentration to low concentration
solute=sugar(other),solvent=water
The higher the concentration of the solute increases the osmotic pressure.
water diffuses from the more watery to the less watery side of the membrane
osmotic pressure: The pressure due to differences in concentration on either side of a semipermeable membrane
carrier mediated
facilitated diffusion
diffusion with help, where molecules diffuse across cell membrane with assistance of carrier proteins. carrier protein changes shape and molecule is released on the other side of membrane
diffusion takes place from high concentration to low concentration does not require ATP for example amino acids or glucose
carrier proteins: specific, can become saturated, and can be regulated by hormones for example insulin
proteins bind to molecules
bring in glucose and AA
carrier mediated
active transport
process of using ATP to pump molecules across membrane against the concentration gradient
they move from low concentration to high concentration
using active transport a cell can take in or pass out substances regardless of their concentration which is why energy is needed. For example membrane pumps sodium ions and potassium ions which are high in the nerve cells of the body
bring in glucose, certain ions, AA
endocytosis
process that brings materials into the cell
involves the cell absorbing large particles such as proteins or even whole organisms such as bacteria, viruses, from outside by engulfing them with the cell membrane to form a vesicle like a bubble with in the cytosol
brings in cholesterol, iron ions
The cell membrane folds around a particle until the particle is completely enclosed, the vesicles so formed then pinches off and suspended in the cells cytoplasm
exocytosis
release of molecules from the cell, things leaving the cell
contents of vesicle are emptied, vesicle formed inside cell then, membrane of vesicle fuses with the cell membrane and contents emptied into extracelluar fluid
empty secretions such as mucus or digestive juices
carrier proteins
specific: they will only buy to a particular molecule. for example the carrier that transports glucose can not transport any other molecules
saturated: once all the available carriers are occupied, any increase in the concentration of molecules to be transported cannot increase the rate of movement.
Regulated by hormones: they are important in coordinating the activities of carrier proteins
fertilised cell repeatedly divides and differentiates
what is differentiation?
process of specialisation of embryonic cells for particular functions (blood, bone, gland, nerve)
structural levels of human body
cell - tissue - organ - system - organism
tissue
group of cell with similar structure and function epithelial connective muscular nervous
organ
eg stomach
made of different types of tissues working together
stomach has all 4 tissues:
e: lines stomach to protect
m: churns food
n: transmits n impulses to coordinate muscle contractions
c: holds all tissues together
epithelial tissue
covering and lining tissue that protects
lines inside of organs
consist of cells very closely joined together
cells that vary in size in different tissues (thin&flat, column/cube shaped)
mouth lining, outside lung, outer layer of skin
connective tissue
supporting tissue that holds body parts together
made of widely spaced cells separated by noncellular material called matrix
eg: blood, bone, adipose (fat) tissue, ligaments (bone to bone), tendon (muscle to bone), cartilage
under skin there is loose connective tissue
matrix of blood is plasma
muscle tissue
contracting tissue that responds to stimulus
made of long, thin, muscle cells/fibres
responds to stimulus by contacting and relaxing
3 types of muscle tissue
skeletal: (striated/voluntary) attached to bones
arms and legs
smooth: (non striated/involuntary) in walls of many organ
uterus, stomach, blood vessels
cardiac: branched and striated with intercalated discs/involuntary) contacts to pump blood around body
involuntary: something you can’t control
nervous tissue
carries message in form of electrical impulses around body
found in brain, spinal cord, nerves
composed of neurons (nerve cells) with long projections from the cell body
stimulation of a neuron causes messages of to be passed along projections throughout the body
metabolism
total of all chemical reactions/processes occurring in your body
2 types
maintains a balance between energy released and energy used
catabolism
breaking down
large molecules broken down to smaller ones
energy released
cellular respiration
anabolism/synthesis
building up
small molecules built up to larger ones
energy required
amino acids to proteins
glucose to glycogen
lactic acid and oxygen to glucose
fatty acid and glycerol to lipids
enzymes
organic substance (protein) that speeds up chemical reactions without being altered or destroyed in the process organic catalyst (has carbon=organic) without them, chemical reactions would be too slow to sustain life
cellular respiration
glucose+oxygen—>ATP+co2+h2o
occurs in every cell to supply energy
1st stage is anaerobic in cytoplasm
2nd stage is aerobic in mitochondria
stage 1: glycolysis
breaks down one glucose molecule to make 2 two molecules of pyruvate (pyruc=vic acid C3H4O3)
also makes 2 molecules of ATP
occurs in cytoplasm of cell, doesn’t require oxygen
If no oxygen is present, pyruciv acid goes to lactic acid
lactic acid goes to liver nd recombines with oxygen to make glucose
stage 2: Krebs cycle and electron transfer system
Krebs cycle= citric acid cycle
series of reactions where pyruvate is completely broken down to CO2.
Krebs cycle make 2 ATP, electron transfer makes 34 ATP
in mitochondria, requires oxygen
ATP
adenosine triphosphate
made by joining an inorganic phosphate group to ADP (adenosine diphosphate)
phosphate group is joined with a very high energy bond that is easily broken
ATP stored energy in that bond, when the phosphate is removed, energy is released and ATP becomes ADP
energy used by the cell
60%: for heat to maintain temp
40%: forms ATP, used in body for muscle contraction, active transport, synthesis for growth and repair, transmission of nerve impulses, cell division, movement of things in and out of cell.
lactic acid
during high intensity exercise, O2 can’t be supplied fast enough, so muscles burn glucose anaerobically, producing lactic acid
lactic acid build up in muscle is toxic and causes fatigue and pain
lactic acid is taken by the blood to the liver where it is recombined to form glucose then glycogen (storage form of glucose)
oxygen debt
after exercise breathing is heavy so oxygen can be repaid
recovery oxygen: oxygen required after exercise
protein synthesis
process where small amino acids are linked together to make proteins
nutrients x6
substance in our food that is used to growth, repair a nd maintenance of body
organic has carbon. inorganic are transported in blood as ions
carbohydrates
main source of sugar for cells (sugar and starches)
C, H, O always 2x H than O
proteins
broken to amino acids. enzymes are made of proteins and important in metabolism C,H,O,N (S, P) 2 AA: dipeptide 10+ AA:polypeptide 100+ AA: proteins
lipids
fats
C,H,O much less O than carbohydrates
one glycerol molecule and 1/2/3 fatty acid molecules
triglyceride: glycerol + 3 fatty acids
glycerol can enter glycolysis pathway and is broken down to release energy similar to glucose
vitamins
act as coenzymes for many chemical reactions of metabolism
minerals
ions
na, k, ca, cl, i
co factors for enzymes
water
important in metabolism
dissolves substances
activation energy
energy required to start a chemical reaction
usually takes long time for reaction to gain this energy
but enzymes decrease activation energy needed so reactions occur faster
means cells can burn glucose at body temp instead of normally high temp of combustion
substrate
active site
products
substance that acts with an enzyme, locks in with active site if it fits
position where locking occurs,
chemicals resulting from the enzyme reaction
characteristics of enzymes x9
- are proteins, organism synthesises its own enzymes
- specific: catalyses one specific reaction type, no effect on other enzymes eg pepsin only break down protein
- small amount of enzyme catalyses a large amount of substrate
- an enzyme is not used up in the reaction it controls. however it can become inactive and more needs to be synthesised
- enzymes can be denatured (lose shape) by heat and lose catalytic properties
- optimum temp is 37ºC and pH varies. over 45ºC enzymes are denatured
- some only work if a second substrate called co-enzyme (organic) or co-factor (inorganic)are present
- work by lowering energy required to start reaction (activation energy)
- work on a lock and key principle
functions of blood
- transport nutrients and oxygen to cell
- transport co2 and wastes away from cell
- transport hormones to cells
- regulate pH
- thermoregulation
- protect against disease (WBC)🦠
- clotting to prevent blood loss
- maintain water and ion content in bodily fluids 💦
components of blood
liquid: palms 55%
non-liquid: formed elements 45% (cells and cell fragments)
erythrocytes
RBC
suited for o2 and co2 transport
have HGB (protein) and has no nucleus to make room for it ( when combine with o2, HGB is red)
large SA to V to speed up gas exchange
made in bone marrow, destroyed in liver/spleen by macrophages (120 days)😩
small, 8um and flexible to go through narrow capillaries
leucocytes
fight infections/provide immune responses
granulocytes: granular cytoplasm, lobed nucleus
agranular: lymphocytes and monocytes
macrophage is type of monocyte- phagocytic
few minutes to YEARS!!
get rid of dead or injured cells 😭(RIP) and invading microorganisms 🦠
thrombocytes
small cell fragments with no nucleus😔
1/3 of RBC🖕👌
made in bone marrow life span of a week
important in coagulation
plasma
91% water
rest is dissolved substances
glucose, AA, ions, wastes (urea: waste of protein metabolism), gases
oxygen transport x2
3% dissolved in plasma
97% carried in HGB to make oxyhemoglobin
this bond is v loose to breaks down easily to release oxygen
when o2 conc is high (capillaries in lungs), o2 combines with HGB easily
when o2 conc is low (cells) oxyhemoglobin breaks down
co2 transport x3
8% dissolved in blood plasma
22% combines with HGB to form carbaminohaemoglobin
70% carried in plasma as bicarbonate ions (HCO3-) (H+)
co2 diffuse into plasma because of con grad, most of it reacts with water to from carbonic acid. this then dissociates into hydrogen ions and bicarbonate ions
in lungs:
8% diffuses out
22% breakdown then diffuse
70% ions recombine to carbonic acid then breaks down by enzymes to water and co2, then diffusion
arteries
carry blood away from the heart
carry oxygenated blood
have thick, smooth, muscular walls with elastic fibres
no valves
high pressure blood because it is closer the heart, increase as ventricles contact
further down in skin because it contains high pressure blood
veins
carry blood toward the heart
carry deoxygenated blood
thin, relatively inelastic (pressure is constant) walls with little muscle
have valves
blood is under low pressure because most of the pressure is lost as it flows through the tiny capillaries