stuff you need to know

What is the cell theory

The cell theory is a fundamental idea of biology stating that:

- All cells arise from pre-existing cells

- All living things contain cells

- Cells are the smallest functional units of life

- Cells contain inherited information, used as the instructions for growth, functioning and development

Main proteins in the cell membrane and their function

Glycoproteins- allow cellular recognition and immune responses

Glycolipids- surface receptors

Channel proteins- aid in passage of substances through membrane

How do unicellular organisms maintain homeostasis examples

through their pores which aid in water availability

how did life arise

through shallow mud pools or inorganic molecules of amino acids transforming into more complex polymers.

other theories of rise of life

- Theory that first cells did not require oxygen to survive, due to Earth's hostile conditions

- Photosynthetic bacteria theory which describes that the rise of bacteria with photosynthetic abilities is the reason for an increase of O2 in the Earth's atmosphere

- Aerobic organisms arose after the increase in O2 in the atmosphere, as cells where able to become more complex and serve more functions due to using O2 in their metabolism

- RNA world hypothesis suggests that first life was formed using RNA as a genetic code due to its self-replicating abilities

role of RNA in first simple cells

RNA-

- Stored information through its nucleotide sequence

- Had self-replication abilities, therefore was able to transmit information to daughter cells

- Single stranded, therefore simpler

- Able to metabolize and break and form nucleotides for self-replication

how does fossil evidence prove prokaryotic cells were first

stromatolites which show that prokaryotes existed approximately 3.5 bya by bacteria mats being trapped and compressed by sediments forming rocks

why and how are the base-pairing rules and method of DNA replication universal.

This means base pairing rules apply to all life on earth, so even DNA from one species can be transcribed and translated by another species' organism, such as Human DNA being read by bacteria to make insulin

explain termination in DNA replication

There is now new DNA formed containing one strand of original or parent DNA, and one strand of new DNA. The new DNA recoils into double helix structure and into chromosomes which will later split into a chromatid

process of gene coding

Genes are segments of DNA which code for polypeptides which make up proteins such as enzymes which are involves in gene regulation and metabolism control.

what are vacuoles filled with

water, solutes, sugars and amino acids

examples of vesicles

such as food vesicles or contractile vesicles

function of vacuole/vesicle

to maintain water/solute concentration within the cell, store waste products and help with the shape and growth of the cell.

structure of golgi body

a stack of flattened sacs made of smooth membrane.

function of golgi body

secrete proteins and carbohydrates made by the cell, transports these by packaging them into vesicles for exocytosis

function of cytoskeleton

give the cells their shape, hold organelles in place, strengthen cells and allow cell movement.

Microfilaments

are made of the protein actin, it allows for cell movement such as contraction of muscles

how do we keep our tolerance conditions stable?

we need regulatory control mechanisms through the fluctuations in our tolerance limits

nervous and endocrine systems are important in...

regulation and control of the body

Chemoreceptors

respond to chemicals for taste and smell and respond to co2 or o2 changes

negative feedback

A stimulus disrupts homeostasis in a controlled condition which is detected and monitored by receptors, which then send an input to a control center, receiving the input and sending an output to an effector which carry out a response to alter the controlled conditions, returning homeostasis by inhibiting/reducing/getting rid of the stimulus.

how does sharing a common gene pool indicate same species

Members of a species share a common gene pool and are reproductively isolated from other species.

what are amino acids

Amino acids are the basic units from which proteins are made, this sequence determines is nature/shape, which determines its function.

what are proteins

Proteins are macromolecules that are vital to cellular function. They are made from 1 or more polypeptide chains and transcribed from DNA

secondary structure of protein

the shape the polypeptide chain takes, either alpha helix (coils) or beta pleated sheets (folds) by the hydrogen bonds of chains, this is determined by the primary structure of a protein

what are antibodies

Globular proteins involved in defending the cell against foreign bacteria by binding to them

fibrous proteins

Fibrous proteins are only found in animal cells, their polypeptide chains are folded into long fibers, hey are water insoluble and are tough and stretchy.

Functions include structure and contractile

how do enzymes lower activation energy

Activation energy describes the energy required for a reaction to take place. Enzymes lower the amount of energy required for a reaction to take place by:

- Bringing reactants together in the correct orientation

- Straining chemical bonds of the substrate

- Making reaction happen in small steps

Enzymes make it easier for a reaction to take place, they may provide an alternative pathway, lowering the activation energy.

what is energy

Energy is defined as the capacity to do work, it is required for movement of substances and cells, synthesis such as creating large proteins or lipids and maintaining the stability of the cell's water/solute balance or pH.

autotrophs which are not photosynthetic

There are also organisms which are autotrophs undergoing chemosynthetic reactions in which prokaryotes make food from simple raw materials.

how is photosynthesis regulates

by enzymes found in the grana and stroma in the chloroplasts in plant cells

describe the energy lost/required during respiration

The breakdown of glucose in the presence of oxygen releases energy. This is due to the fact the energy required for the breaking of the bonds in glucose and oxygen is less than the amount released when carbon dioxide and water molecules are formed. This extra energy can be used by the cell or lost as heat.

what type of process is aerobic respiration

catabolic

aerobic respiration

Aerobic respiration begins with Glycolysis-

This is where Glucose is converted into 2 pyruvate molecules and 2 ATP molecules

This occurs in the cytoplasm. Then. In the mitochondria,

The pyruvate is transformed into an acetyl co-enzyme A which is converted into carbon dioxide and water

Through phosphorylation, ADP is converted to ATP and an additional 36 ATP is produced.

This is the process of the Krebs's cycle which occurs in two rounds and produces enough energy for phosphorylation. Krebs's cycle also produces 6 carbon dioxide molecules and water molecules, with 6 oxygen molecules being used.

how does the mitochondria provide different regions for different reactions to occur

- The space between the outer and inner membrane

- The inner membrane

- The space inside the inner membrane

Each of the enzymes and proteins necessary are located in a particular region.

what is the role of the CNS

The role of this system is to detect changes in the brain, receive stimuli from the PNS, process information and send nerve impulses to effectors to bring about a response

what other nerves does the PNS contain

The PNS contains nerves from the Voluntary/Somatic Nervous System and the Involuntary/Autonomic Nervous System .

role of PNS

The role of the PNS is to connect the CNS to all parts of the body, peripheral nerves originating from the brain are called cranial nerves, nerves coming from the spinal cord are called spinal nerves.

what are nerves

Nerves are bundles of many neuron cells whose axons run parallel to eachother enclosed in protective sheaths.

what cells make up the nervous system

Neurons and glial cells make up the nervous system. Glial cells provide structural land metabolic support to neurons. Neurons conduct and transmit impulses throughout the body by the nerve pathway, consisting of many neurons with synapses between them.

how does a nervous impulse travel

The nerve impulse travels along the axon, but stops at the synapse. This nerve impulse is transmitted through a neurotransmitter to the next neuron through the synapse. The nerve impulse can only go from the dendrite to the axon terminal.

what are sensory neurons

Sensory neurons detect stimuli and send nerve impulses to interneurons in the CNS. They detect stimuli through the receptors on the nerve endings

interneurons

Interneurons receive nerve impulses from sensory neurons and transmit them to motor neurons. They are located in the CNS, and they are multipolar meaning they have multiple processes extending from their cell body. Brain interneurons have longer axons than spinal interneurons.

nerve pathway from receptor to effector

A stimulus is detected by a receptor which triggers a nerve impulse.

This travels along sensory neurons towards the spinal cord of CNS and is transmitted to the brain.

The information is processed by the brain and through interneurons an impulse is transmitted down the spinal cord along a motor neuron.

This carries an impulse to an effector to carry out a response.

what do excitor hormones do

stimulate nerve impulses.

neuromuscular junction is..

The site where a neurotransmitter (acetylcholine) reaches a muscle cell

what happens to neurotransmitters after secretion/transmission

diffuse away, become absorbed or are destroyed by enzymes.

reflex response arc

Receptors -> sensory neurons -> spinal cord -> interneuron -> motor neurons -> effectors -> response

how did mutations change chromosomes

Firstly, chromosomes became linear through mutations as DNA was becoming larger, therefore tightly coiling DNA up into linear chromosomes allowed for easier replication when dividing cells. Also, DNA was getting more complex due to the rise of exons and introns within the sequence.

What is phenotypic expression

Phenotypic expression of a gene refers to its physical, biochemical, or physiological characteristics it produces. Some may be determined by genes or the environment.

how are Products of other genes can affect transcription and translation

Genes are regulated to be transcribed using transcription factors. These regulatory proteins control gene expression by turning the gene on by binding to its promoter region or turning them off by blocking the attachment to RNA polymerase to DNA. Transcription factors can be activated by specific hormones.

what are Environmental effects on transcription and translation

Increased UV exposure, skin colour change

Higher light intensity, taller plant

Malnutrition, decreased body size

how do cells specialise

Zygote provides differentiating cells which can become specialized into cells which become tissues and organs

Stem cell-> specialized cells -> tissues

*all cells start of as identical stem cells, through gene expression of turning certain genes off and on, they differentiate and join with other similarly differentiate cells o form tissues.

epigenetics

Epigenetic changes refer to the changes in phenotypic/gene expression

how can epigenetic modifications in genes that control cell division, such as changes in DNA methylation, can lead to cancer.

There are genes called tumor suppressor genes which regulate cell division and decrease the incidence of cancer. Methylation of these genes prevents their transcription and reduces their function.

Methylation in CGG repeats in FMR1 gene leads to Fragile X

Mutation rate can be increased by:

ionising radiation

high energy radiation

- mutagenic chemicals

smoking

- viruses.

Viruses are able to incorporate their DNA into the hosts DNA.

Some mutations can effect one nucleotide or one gene which may produce minor, major or no effects at all, Most mutations disadvantage the organism.

Explain how inheritable mutations can lead to changes in the characteristics of the descendants.

Mutations inherited via gametes will appear in the zygote and then in every somatic and germ cell of that individual. Genetic diseases include hemophilia, thalassemia etc. Some mutations involve parts. Whole chromosomes which have high impacts e.g Downs syndrome.

why do cells depend on the exchange of materials to survive

Cells depend on their surroundings by obtaining materials critical to their function. They also need to remove wastes as a high conc may create a toxic environment. The cell membranes structure heavily facilitates this.

osmotic pressure...

maintains cell shape and support

too little water in plant cells

can make it become flaccid.

how does ATP work in active transport

This can occur through sodium pump channels with ATP transferring a phosphate group to the protein which allows it to change in shape and allowing substances across.

why is the cell membrane semi-permeable

If everything could move through the membrane,

- The cell would lose its identity

- The cell would be indistinguishable from the environment

- Contents of the cell would diffuse out

the endocrine system is involved in

coordination and control

amino acid derivative hormones

adrenaline and thryoxine

peptide hormones

anti-diuretic hormone

protein hormones

insulin

steroid hormone

aldosterone which increases the sodium reabsorption by kidneys

what are hormones

Hormones are carried in the blood to exert metabolic effects on target cells, after their role they are broken and excreted. Hormones are produced in small amounts but have long lasting effects.

Hormones reach target cells via complementary binding, they recognize the hormone and trigger an effect

stimuli for secretion of hormones

Stimuli for secretion of hormones include nerve impulses, changes in ion or nutrient levels in the blood or direction of another hormone producing gland.

what does adrenaline do

- increases heart rate

- increases rate of breathing

- increasing cell metabolism

- stimulates pancreas to increase glucagon secretion which initiates release of glucose from liver to blood

- increase in blood pressure and blood flow to brain

- brain is put in a heightened state of awareness

- decreases blood flow to gut and kidney

explain how a mutation in just 1 nucleotide base could produce such a vastly different cell.

A change in one nucleotide can result in a different amino acid being inserted in the polypeptide at that location. A different amino acid will have different chemical properties and will result in the protein having a different shape, thereby changing its function. or A change in one nucleotide can change the codon at that location to a stop codon, which would mean the polypeptide was too short and completely non-functional.

Explain why scientists are able to identify any particular chromosome.

each chromosomes have genes that are specific to it

discuss design and uses of new proteins

Design: new proteins may be designed from scratch or be modifications of existing proteins. Once the amino acid sequence is determined, a gene can be constructed using the genetic code. When the gene is transferred into bacteria or yeast cells, it can be used to make the protein which can then be harvested. Uses: artificial blood for use in emergencies, inhibitor molecules that bind to the surface of a virus to block its entry into a host cell, an enzyme that can cut apart gluten molecules in food to help gluten intolerant people, hollow protein spheres that can enclose and carry molecules like pharmaceuticals or genes in the bloodstream

how is DNA extracted from cells?

- Cell walls and membranes of cells being broken and releases cellular contents and DNA

- Centrifuge is used to separate solids from dissolved DNA

- DNA is precipitated using alcohol, then centrifuged to separate DNA from salts and sugars

describe the process of PCR

goal: amplify tiny sequence of DNA

PCR or polymerase chain reaction is a process where segments of DNA are largely replicated for analysis. PCR occurs starting with a test tube filled with free nucleotides, heat resistant enzymes of DNA polymerase, DNA sample and primers which provide the starting sequence for DNA replication.

Firstly, the DNA strands are separated by heating at 98 C for 5 mins

Then the strands are cooled to 60 C enabling the primers to attach to the separated strands

The sample is warmed up again to 72 C which enables DNA polymerase to bind to the primers on both strands and initiates the synthesis of a new complementary strand of DNA using the free nucleotides.

what is electrophoresis

Electrophoresis is a process used to separate large amounts of molecules depending on their size, charge etc. This can be used to determine DNA sequences by using gel electrophoresis. DNA samples are placed in the wells of one side of a block of agar, they are covered with a buffer solution.

A current is turned on and the negatively charged DNA moves towards the positively charged electrode, smaller fragments of DNA moving faster down the gel.

what is a electropherogram

Automated method of electrophoresis using dye labelled nucleotides, data collected is uploaded to a computer software, creating an electropherogram

what is DNA profiling

the analysis of DNA fragments to determine whether they come from the same individual

what are VNTRS

VNTRs, variable number tandem repeats which are non-coding repeats of DNA. These can be extracted from DNA using restriction enzymes and multiplied via PCR.

VNTRS are then analyzed in gel electrophoresis displaying the individuals unique banding pattern,

how are STRs found

Fluorescently tagged primers are used in PCR process to amplify STR regions, smaller fragments moving faster during electrophoresis. Each STR is detected and displayed in an electropherogram.

ethical issues of collecting genetic info

Insurance companies may ask to see DNA profile for life insurance, could be placed in wrong hands no consent, prerequisites for employers

Why is it important for metabolic pathways to have regulated steps

These regulated steps also allow for specific enzymes to produce intermediate compounds to further the pathway.

why are specific enzymes important in metabolic processes

Without specific enzymes, reactions would occur too slowly, the specificity of the enzyme's active site requires every step in a metabolic pathway to be catalyzed by different enzymes.

examples of chemicals interfering with cell metabolism

Poisonous substances interact with cell metabolism like carbon monoxide binding to hemoglobin and blocks the reaction between it and oxygen in red blood cells.

Lead acting as a non-competitive inhibitor to certain enzymes.

Centrosome

A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. Contains two centrioles.

Centriole

Cell organelle that aids in cell division in animal cells only

Communication and Collaboration

· Science is a global enterprise that relies on clear communication, international conventions, and review and verification of results.

· Collaboration between scientists, governments and other agencies is often required in scientific research and enterprise.

Development

· Development of complex scientific models and/or theories often requires a wide range of evidence from many sources and across disciplines.

· New technologies improve the efficiency of scientific procedures and data collection and analysis. This can reveal new evidence that may modify or replace models, theories, and processes.

Influence

· Advances in scientific understanding in one field can influence and be influenced by other areas of science, technology, engineering, and mathematics.

· The acceptance and use of scientific knowledge can be influenced by social, economic, cultural, and ethical considerations.

Application and Limitation

· Scientific knowledge, understanding, and inquiry can enable scientists to develop solutions, make discoveries, design action for sustainability, evaluate economic, social, and environmental impacts, offer valid explanations, and make reliable predictions.

· The use of scientific knowledge may have beneficial or unexpected consequences; this requires monitoring, assessment, and evaluation of risk, and provides opportunities for innovation.

· Science informs public debate and is in turn influenced by public debate; at times, there may be complex, unanticipated variables or insufficient data that may limit possible conclusions.

what is speciation

Speciation is the evolution of two or more species from a common ancestor

how do organisms fail to recognise eachother in allopatric speciation

no gene flow between populations, become so different from different selection pressures

How does polyploidy occur?

Polyploidy occurs when chromosomes do not separate after duplication in mitosis, thus having homologous chromosomes to pair during meiosis

adaptive radiation

Adaptive radiation is the sudden emergence of species from a common ancestor, usually due to change in environments and different selection pressures.

What is aldosterone?

A steroid hormone made by the adrenal cortex (the outer layer of the adrenal gland). It helps control the balance of water and salts in the kidney by keeping sodium in and releasing potassium from the body. Too much aldosterone can cause high blood pressure and a build-up of fluid in body tissues.

what is gene technology

Gene technology is the analysis of DNA, artificial manipulation of genes and includes inserting foreign genes into other organisms.

ti plasmids

a particular plasmid used to introduce new genes into crop plants. Advantages: to help produce plants with desirable traits, resistant to diseases

what is CRISPR

CRISPR describes Clustered Regularly Interspaced Palindromic Repeats.

Bacteria have certain enzymes which possess the mechanisms store some of the invading virus DNA into their own. If the virus attacks later, the bacteria recognize this and creates a complementary RNA strand which is stored. This strand is loaded into an enzyme named Cas9 which finds the complementary DNA, binds the RNA and cuts the invading virus. This destroys the virus.

DNA can be inserted into an organism using Cas9 and CRISPR too. Cas9 cuts in the correct location, then another mediating protein ads the desired piece of DNA in the cut location.

how do scientists design proteins

Proteins are designed by scientists examining the shape they want the protein to take then determining what amino acid sequence will produce this shape. The genetic code is then used to construct a DNA sequence which will transcript the specific chain of amino acids. This DNA is incorporated into plasmids, which will reproduce and produce these proteins which are then harvested.

Mitosis: Prophase

Spindles fibers form

Centrioles move to opposite sides of the cell

Nuclear membrane dissappears