A1: Cells, Tissues, And Biological Molecules Flashcards
What does the cell membrane do?
Controls what enters and excites the cell
What does a Centriole do?
Helps the cells to divide
Cytoplasm?
.Cell like liquid containing organelles
.Gives the cell shape
.Site of many reactions
Mitochondria?
The site of aerobic respiration and its where ATP is made.
It also has a double membrane.
Nucleus?
. Every Eukaryotic cell has one
. Controls the cell by storing genetic information
Nucleolus?
Makes ribosomes
Ribosomes?
Makes up proteins out of amino acids using instructions from nucleus
Rough endoplasmic reticulum?
Layers of membrane covered in ribosomes
Smooth endoplasmic reticulum?
Layers of membrane that make lipids and carbohydrates.
Golgi apparatus??
Packages and modifies proteins ready for export from the cell.
Makes lysosomes.
Lysosomes?
Contains digestive enzymes for breaking down waste inside the cell.
Cytoskeleton?
Gives the cell shape
What does hydrophobic mean?
Repels water = fatty acid tails
What does hydrophilic mean?
Attracts water = phosphate heads
What’s a glycoproteins?
Found on the outside of the cell membrane.
Hydrophilic nature means they can function in aqueous environments.
Important for cross-linking cells and proteins e.g collagen to add strength to the tissues.
Cell recognition and communication .
Binds to hormones
What’s a glycolipid?
Maintain the stability of the cell membrane.
Cell recognition and communication.
What does cholesterol do in the cell membrane?
Regulates fluidity and stabilises the membrane ( provides support).
Chanel protein?
They make hydrophilic tunnels and allow target molecules to pass through by diffusion.
What does partially permeable mean?
Only allows particular substances to cross it.
What is a fluid Mosaic?
Phospholipid molecules move around each other within a layer relative to one another in different shapes and sizes.
Vesicle?
Transport materials around the cell or out of it.
What is a carrier protein?
Uses energy to transport substances.
Intrinsic protein
They are firmly in bedded within the phospholipid bilayer.
Extrinsic protein
Loosely bound to the outside of the plasma membrane.
What is simple diffusion?
The movement of substances from an area of high concentration to an area of low concentration.
This happens because of the random motion of particles.
Doesn’t require any extra energy.
What are the rules for crossing the phospholipid bilayer?
If it is charged, polar or large it can not cross.
But water is polar and it can cross.
Why are amino acids and sugars not able to pass the bilayer?
Because they are polar and will be repelled by the fatty acid tails.
What is facilitated diffusion?
Molecules move from a high to low concentration. It is a passive process so it doesn’t require any extra energy. It diffuses with the aid of transport proteins.
What is active transport?
Molecules move from a low to high concentration. It is a active process, so it does require extra energy. It diffuses with the aid of transport proteins.
The extra energy is ATP
What is osmosis?
Osmosis is the diffusion of water from an area of low solute concentration (high water potential), to an area of high solute concentration ( low water potential) through a partially permeable membrane.
What is the difference between endocytosis and exocytosis?
Endocytosis is the hormone going into the cell.
Exocytosis = exists the cell.
What is phagocytosis?
It is a type of endocytosis.
Phagocytes are white blood cells that use phagocytosis to engulf and destroy pathogens.
- The pathogen interacts with the phagocyte receptors.
- Phagocyte engulfs the pathogen and becomes a phagosome.
- A lysosome breaks the pathogen down into proteins and other molecules.
Define magnification
Th degree to which something can be viewed larger than it is.
Define resolution
The shortest distance between two points on a specimen that can still be distinguished by the observer.
Features of a light microscope
Image beam: light
How is beam focused: glass lens
Max mag: x 10000
Max res: 100 nano meters
Can a live specimen be used: yes
Cost : cheaper
Staining required: yes
True colour seen: yes
Can image be viewed directly: yes
Features of electron microscope
Image beam : electrons
How is beam focused: magnets
Max mag: x1000000
Max res: 1 nano meter
Live specimen?: no
Cost : expensive
Staining of specimen: yes
Tue colour be seen: no
Can image be viewed directly: no
Equation for magnification
Magnification = image size divided by actual size.
What measurements do we use in microscopy?
We only millimetres.
There are 1000 nano meters (nm) in 1 micrometer
There are 1000 micrometers in 1 millimetre
Converting for microscopy
Nanometre Micrometer Millimetre
X1000 < X1000
%1000 > %1000
What is DNA short for?
What does it make?
Deoxyribonucleic acid.
It’s the code inside all of our cells and it makes proteins.
What is one monomer subunit of DNA called?
Nucleotide
What bases are purine and which are pyrimidines?
Purine = adenine and guanine = 2 ring
Pyrimidines = cytosine and thymine = 1 ring
Where is DNA found in eukaryotic cells and what is its shape?
Nucleus and double helix
Name the 4 bases of DNA
Adenine
Cytosine
Guanine
Thymine
What makes up a nucleotide?
A phosphate group, a Penrose sugar (deoxyribose) and a nitrogenous base (ACGT)
DNA STRUCTURE
A molecule of DNA is formed by millions of nucleotides joined together in a long strand by condensation reactions.
The DNA strands are on the outside. The two strands are held together by weak hydrogen bonds between complementary base parings.
How many hydrogen bonds are there between the complementary base pairings?
A and T have 2 hydrogen bonds (straight letters)
G and C have 3 hydrogen bonds ( curvy letters)
What does RNA stand for?
Ribonucleic acid.
Differences between DNA and RNA
DNA has deoxyribose sugar and RNA has a ribose sugar.
RNA is single stranded and DNA is double stranded.
RNA has Uracil and DNA has Thymine.
mRNA- messenger RNA
. Contains Uracil instead of Thymine
. Its a copy of one gene
. It can leave the nucleus
. Carries the code for protein synthesis from the DNA to the ribosome.
tRNA - transfer RNA
. Shorter than DNA
. Has 3 exposed bases called an Anticolon
. Carries one amino acid, specific to 3 bases that make up the anticolon
. Clover leaf shape
. Binds to the large sub unit of a ribosome
What’s the full name of ATP?
Adenosine Triphosphate
Carry’s 3 phosphates.
How do cells get ATP?
Aerobic respiration
Anaerobic respiration
When does ATP release energy?
When it is hydrolysed (the addition of water)
When can ATP be used?
Active transport
Chromosomes being separated in cell division
Structure of ATP molecule
. 3 phosphates : the third phosphate has an unstable bond. When this bond breaks (is hydrolysed) and energy is released.
. Ribose sugar
. Adenine ( nitrogenous base )
ADP structure
. 2 phosphates: diphosphate
. Adenine (nitrogenous base)
. Ribose sugar
Respiration
Energy from glucose. Is released in respiration, and this is used to turn ADP back to ATP using the energy released from reacting glucose with oxygen in respiration.
Respiration occurs in the mitochondria.
Energy is required to rejoin one phosphate back on to ADP to make ATP.
ATP > hydrolysis reaction > h20 releases energy ADP+pi > h20 requires energy > condensation reaction > ATP.
What is ATPase ?
It is an enzyme that hydrolyses ATP.
When ATP IS hydrolysed a water molecule is inserted into it breaking the high energy bond. The ATP is broken down into ADP and pi. This process releases energy.
It’s role in the cell is to speed up the break down of ATP.
What is glycolysis?
What does the term glycolysis mean?
Where does glycolysis take place?
It’s the first stage in aerobic and anaerobic respiration.
It means sugar breaking.
It takes place in the cytoplasm.
Process of glycolysis and number of carbons
- Glucose is phosphorylated using 2 ATP, making fructose disphosphate
- Fructose bisphosphate then splits into 2 molecules of glycerate 3 phosphate
- Glycerate 3 phosphate is converted into pyruvate making 4 ATP and 2 NADH per pyruvate.
Glucose: 6 carbons Fructose bisphosphate: 6 carbons Glycerate 3 phosphates: 3 carbons
Pyruvate: 3 carbons
Anaerobic respiration
Takes place in the cytoplasm of cell when there is no oxygen. In humans if there is a lack of pyruvate made by glycolysis it is converted in to lactate.
This recycles the NADH back to NAD+ allowing glycolysis to continue. This means that the cell can still gain 2 ATP molecules per glucose.
Advantage is you don’t need oxygen
Disadvantage is it only releases 2 ATP
Explain the link reaction
The pyruvate is actively transported into the mitochondrial matrix. Here, a molecule of carbon dioxide is removed and some more NADH is produced, leaving a compound called Acetate. Acetate then combines with coEnzyme A to form Acetyl coenzyme A.
The 3 products of the link reaction are: (2 of each will be made per glucose)
. Acetyl coenzyme A x2
. Carbon dioxide x2
. NADH x2
What are the two high energy electron carriers that donate electrons to the electron transport chain?
ETC proteins
How are hydrogen ions moved from the matrix to the inter membrane space?
Active transport
Where is there a high concentration of hydrogen in the mitochondria? Where is there a low hydrogen concentration?
High = inter membrane space
Low = matrix
Why can’t hydrogen ions just diffuse back into the matrix between the phospholipid’s of the inner membrane?
Because they are charged and will be repelled by the fatty acid tails.
How do the hydrogen ions diffuse back into the matrix of the mitochondria?
By facilitated diffusion
What reaction does ATP synthase catalyse?
Condensation reaction
What is the term for the production of ATP at the electron transport chain?
Oxidative phophorylation
What accepts the electrons after they have gone through the electron transport chain?
The hydrogen
The ECT on the cristae of the mitochondria is a bit like the light dependent reactions of photosynthesis. Describe how the mitochondrial ETC uses high energy electrons to make ATP.
The NAD+ and FAD+ loose their electrons to the ETC and their hydrogens. The electrons travel through the phospholipid bilayer by ETC proteins and the hydrogen goes to the inter membrane space via active transport. Then they go back through the ATP synthase via facilitated diffusion. The ATP synthase spins which causes the ADP to Tuen into ATP by a condensation reaction.
Mitosis - interphase
. Consists of G1, S, and G2
. G1 phase is period of intense growth
. S stands for synthesis or replication of DNA
. G2 cell continues to grow and prepare for cell division
. Prior to G2 the centrosome is duplicated. The individual chromosomes are not visible until they coil up during mitosis
. More than 90% of the life of a cell is spent in the interphase.
Mitosis - prophase
. First phase of mitsis
Mitosis - metaphase
- The nuclear envelope has completely disappeared and the centrioles are now at opposite ends of the cell.
- Th chromosomes are pulled to the middle of the cell ( the equator) using the micro tubules.
Mitosis - anaphase
. Shortest phase of mitosis
1. Microtubules pull the two sister chromatids apart allowing then to become two identical chromosomes
2. At the same time the cell elongates as the microtubules not attached to the kinetochores lengthen.
3. By the end , the cell has twice the original number of chromosomes and they are genetically identical.
Mitosis - telophase
- A visible nuclear envelope begins to form around each set of chromosomes and the nucleoli reappear.
- The chromosomes become less condensed and unfold into chromatin while the microtubules attached to the spindle break down.
- The cell continues to elongate and mitosis is complete.
Mitosis - cytokinesis
The cytoplasm divides its contents into 2 identical daughter cells. In animal cells a cleavage furrow forms as microfilaments contract and pinch the cell in two. In plant cells a cell plate forms allowing the creation of a cell wall.
What is homeostasis?
Homeostasis is the maintenance of a state of dynamic equilibrium.
In real terms its the maintenance of a constant internal environment despite internal or external changes.
What factors are controlled by homeostasis??
- pH
- temperature
- water potential
- blood glucose levels
What is negative feedback?
Negative feedback means that when there is a change away from the normal set point, corrective processes take place to return the change back to normal.
What are the stages of negative feedback?
- Stimulus- produces change in variable
- Receptor- change detected by the receptor
- Control centre/ co-ordinator- information sent along afferent pathway to it.
- Effector- information sent along efferent pathway to the effector
- Response- the response of the effector feeds back to influence magnitude of stimulus and returns variable to homeostasis
What is thermoregulation?
The maintenance of normal body temperature = around 37°C
What is abnormally high temperature called?
Hyperthermia
What is the body’s response to a rise in temperature?
Stimulus - body temp rises e.g sun , infection
Receptors - thermal receptors in the skin and around internal organs stimulated
Nerve impulses
Control centre - temperature control centre in brain switches on heat- losing mechanisms
Nerve impulses
Effectors - sweat glands , arterioles in skin dilated, behaviour altered
Response - body’s temperature decreases
What is the gland in the brain that coordinates temperature control ?
Hypothalamus of the brain
What are the receptors in the thermoregulatory centre?
They are called thermoreceptors
They monitor the temp of blood as it passes through the brain thus monitoring body’s core temp.
What happens to sweat glands if body temp too high?
They secrete sweat onto the skin where it evaporates. The evaporation of water requires a relatively large amount of energy and so sweating is an effective way of cooling you down.
What happens to the hairs on your skin if your too hot or cold?
- When body temp falls signals from the heat gain centre cause there muscles to contract. This allows them to stand on end and trap an insulating layer of air close to the skin .
Not that effective as body hair los through evolution - If your too hot they lay flat on the skin.
How do your skeletal muscles raise your temp?
Heat gain centre of hypothalamus sends signals to your skeletal muscles to cause them to contacts and relax repeatedly. This is shivering. Heat is generated by the increased rate of respiration needed to supply the ATP for the contractions to take place.
Causes of hypothermia
. If core team increases greater than 37.5-38.3
. When there is an excess Production of the heat of ineffective heat loss
Symptoms of mild and severe hypothermia
Mild
. Sweating
. Rapid breathing
. Vomiting
. Headaches
Severe
. Unconsciousness
. Organ failure
. Death
. Excess heat ca cause injury to the skin resulting in burns that could require amputation.
Causes of hypothermia
Decreased heat production or increased heat loss such as alcohol intoxication or low blood sugar
Symptoms of hypothermia mild and severe
Mild
. Shivering
. Drowsiness
Severe
. Unconsciousness and death
. Frost bite
. Chilblains - cold causes perenalt damage to small blood vessels in the skin resulting in redness and itching
What is a superficial burn 1st degree
Tissue involved is epidermis and it causes redness and swelling, minimal skin damage, no blisters
Partial thickness 2nd degree
Epidermis and upper dermis tissue involved.
Same as superficial but with blisters
Full thickness 3rd degree
Destruction of Epidermis and dermis tissue
Relatively painless due to the destruction of nerve endings
What happens to cells during frostbite?
Water within the cells begins to freeze
What parts of the body tend to get damaged
Fingers
Toes
Nose
Tips of ears
Frostbite
Mild frostbite is reversible severe may result in amputation.
