paper 1 Flashcards
what is a haploid
A sex cell that contains one set of chromosomes
what is the buriet test
test for proteins
Pottassium hydroxide is mixed with a solution of food two drops of copper sulphate then added
if it turns purple from pale blue there is protein ins the food
What are the stages of mitosis
- Interphase
2.prophase - metaphase
4.anaphase
5.telophase
6.cytokinesis
how are microvilli adapted for digestion
increased surface area means there is more area for molecules to be absorbed.
What is the role of chloroplasts in the plant cell
The chloroplast contain chlorophyll which transfers which traps energy transferred from the sun the energy is used for photosynthesis
what is catalyse
found in most cells but especially liver cells
breaks down hydrogen peroxide made in many cell reactions to water and oxygen
what is the verbal cortex in the brain
outer layer of the brain
responsible for memory consciousness and personality
what is the cerebellum
underneath the cerball cortex
cobtrolls balance muscular activity coordination of movement
what is transcription (protein synthesis)
Inside the nucleus section of the DNA where the gene is gets unziped. A copy of the DNA sequence is made
This copy is called MrNA
the transcript is used to make the protein
what is amylase
found in the saliva and small intestine
its an enzyme that breaks down starch to small sugars such as maltose
what are enzymes
proteins that function as biological catalysts
the substance that enzymes work on are called substrates
the speed up the retention without being changes
what is the nucleus
contains genetic information including DNA which controls the cells activities
what is the cell wall
only found in plant cells
made up of cellulose and supports and protects the cell
what is the mitochondria
where aerobic respiration takes place
its where most energy is released
it contains the enzymes for anaerobic respiration
what is a diploid
a cell that contains two sets of chromosomes
what is the difference between mitosis and meiosis
mitosis produces identical diploid cells for growth and repair
meiosis produces two non identical sex cells or gametes these fuse to form a diploid fertilised egg cell during fertilisation
what are ribosomes
tiny substances where protein synthesis occurs
what is the ethanol emulsion test
test for fats and oils
the food is mixed with ethanol and shaken some of that mixture is poured into water and shaken again Fats and oil dissolved in the ethanol float to the surface forming a cloudy emulsion
what is a eukaryotic cell
Cells of animals, plants and fungi are called eukaryotic cells. Eukaryotic cells also have other structures in the cytoplasm which have membranes around them they do have a nucleus
what is a prokaryotic cell
don’t have a nucleus
most of the genetic information is stored in a single DNA loop in the cytoplasm
Bacteria are prokaryotes
what are the 5 ways pathogens can spread
- Virus droplets sprayed in air and breathed in
- water drinking infected water eg cholera
- direct contact eg shaking hands
- food
- vectors organisms that spread diseases but don’t get it themselves eg mosquitoes
how is bacteria treated in humans
which antibiotics
what is a pathogen
Pathogens are disease-causing viruses, bacteria, fungi or protists, which can infect animals and plants. Humans have an immune system, which can defend them from pathogens.
what is the cell membrane
it is semi permeable and controls movement of substances in and out of the cell
what are the 4 dna bases
These bases are adenine (A), cytosine (C), guanine (G) and thymine (T)
A always pairs with t and c with g
what is the cytoplasm
a jelly like material that contains dissolved nutrirents and salts and structures called organelles its where a lot of chemical reactions happen
what is Cholera
Symptoms- Diarrhoea
Pathogen- A bacterium
how it spreads- Contaminated water
how to prevent- making sure people have access to clean water supplies
what is Malaria
Symptoms- high temperature, sweats and chills. Damage to red blood cells and in severe cases the liver
Pathogen- A protist
how it spreads- Mosquitoes act as a vector they pass on the disease but don’t get it themsrelfs
how to prevent- Mosquito nets and repellents
what is tuberculosis
Symptoms- Coughing and lung damage
Pathogen- A bacterium
how it spreads- Through the air when the infected cough
how to prevent- infected poeople avoid public spaces and practice good hygiene
what is Stomach ulcers
Symptoms- Stomach pain nausea and vomiting
Pathogen- bacterium
how it spreads-oral transition eg swallowing contaminated water or food
how to prevent- clean water supplies and hygienic living conditions
what is ebola
Symptoms- Haemorrhagic fever (A fever with bleeding)
Pathogen- virus
how it spreads- via bodily fluids
how to prevent- isolating infected individuals and sterilising any possible infected areas
what is charala ash dieback
Symptoms- leaf loss and bark lesions (wounds)
Pathogen- A fungus that infects ash trees
how it spreads- through air by the wind
how to prevent- removing young infected ash trees and restricting the movement or import of ash trees
what is the lyctic cycle (steps)
The lytic cycle involves the reproduction of viruses using a host cell to manufacture more viruses; the viruses then burst out of the cell.
- the virus attaches itself to a specific host cell and injects its genetic material into the cell
- the virus uses proteins and enzymes in the host cell to replicate its genetic material produce the components of new viruses
- the viral components assemble
- the host cell splits open releasing the new viruses which infect more cells
what do viruses have to do in order to reproduce
they have to infect a living cell in order to reproduce host cells
how do plants reduce the risk of infection from pathogens
they have a waxy cuticle that provides a barrier to stop pathogens entering them and it stops water from collecting on the leaves which reduces the risk of infection
also the cell wall creates a barrier
what is immunisation
it involves injecting dead or inactive pathogens into these are antigenic so even though they are harmless your body makes antibodies to help destroy them.
the antigens from the dead or inactive pathogens also trigger memory lymphocytes to be made so if the same types of pathogens get into the body there will already be memory lymphocytes that can cause a fast secondary immune response.
what happens when a new cell enters the body
when a pathogen enters the body for the first time the response is slow beacuse there aren’t many B-lyphocytes that can make the antibody needed to lock on to the antigen
eventually the body will produce enough of the right antigen to overcome the infection meanwhile the infected person will show symptoms of the disease.
what are memory lymphocytes
After the pathogen is removed some of the lymphocytes continue to remain in the immune system. These are called memory lymphocytes. If the same pathogen enters the immune system for a second time, the response is much more rapid.
what are antigens
Antigens are molecules, often proteins, located on the surface of cells that trigger a specific immune response.
what is DNA
DNA is a polymer made from four different nucleotides. These are arranged in a repeating fashion. Each nucleotide consists of alternating sugar and phosphate sections with one of the four different bases attached to the sugar.
What shape is DNA
Double Helix
what is transcription within the process of protein synthesis
When a gene is to be expressed, the base sequence of DNA is copied or transcribed into mRNA (messenger RNA). This process takes place in the nucleus and occurs in a series of stages.
The two strands of the DNA helix are unzipped by breaking of the weak Hydrogen bonds between base pairs. This unwinding of the helix is caused by an enzyme (helicase enzyme).
The enzyme RNA polymerase attaches to the DNA in a non-coding region just before the gene.
R
NA polymerase moves along the DNA strand. Free RNA nucleotides form hydrogen bonds with the exposed DNA strand nucleotides by complementary base pairing to form a strand of mRNA:
Note - RNA nucleotides contain the same bases as DNA, except that T is replaced by U. U base pairs with A.
Because the opposite base bonds with the exposed DNA bases, the strand of mRNA is an opposite copy of the DNA strand (except that U replaces
T) . We call this a complementary copy.
The newly formed strand of mRNA is now ready to leave the nucleus and travel to the ribosome.
what is translation within protein synthesis
Translation is the protein being assembled in the ribosome
Amino acids are brought to the ribosome by transfer RNA.
The mRNA strand travels through the cytoplasm and attaches to the ribosome. The strand passes though the ribosome.
The order in which the amino acids are brought to the ribosomes matches the order of the base triplets in the mRNA. Base triplets are known as CODONs.
tRNA molecules transport specific amino acids to the ribosome which they leave behind shortly after lining up opposite the DNA.
Used tRNA molecules exit the ribosome and collect another specific amino acid.
A chain of several hundred amino acids in the correct order according to the original DNA is then made. This is called a polypeptide.
After translation, the polypeptide is finally folded into the correct shape and becomes a protein.
what is environmental variation
Some examples of variation are not caused by the inheritance of genetics. Whether or not you have a scar or tattoo was not determined when the sperm fertilised the egg to begin your life. This variation is often caused by the environment we live in and so is called
environmental variation
.
what are mutations
Mutations are changes that can occur in genes. These changes are random and can be caused by background radiation and chemicals that we come into contact with, eg the chemicals in cigarette smoke. The change causes an alteration to the base sequence in the genetic code.
who was Mendel and what did he discover
In the mid-19th century Gregor Mendel (1822-1884) studied the inheritance of different characteristics in pea plants. He found that when he bred red-flowered plants with white-flowered plants, all the offspring produced red flowers. This went against the prediction that the colours would blend to produce pink flowers. If he bred these plants with each other, most of the offspring had red flowers, but some had white. This was because the allele for red flowers is dominant and the allele for white flowers is recessive.
This was the basis of our understanding of inheritance. At this point we did not know what a
gene was. One of Mendel’s observations was that the inheritance of each characteristic is determined by ‘units’ that are passed on to descendants unchanged. We now know these as genes.
what are alleles
Alleles. are different versions of the same gene. For example, the gene for eye colour has an allele for blue eye colour and an allele for brown eye colour. For any gene, a person may have the same two alleles, known as homozygous or two different ones, known as heterozygous.
What is the active site in enzymes
Enzymes are folded into complex 3D shapes that allow smaller molecules to fit into them. The place where these molecules fit is called the active site
what is the lock and key hypothesis
In the lock and key hypothesis, the shape of the active site matches the shape of its substrate molecules. This makes enzymes highly specific. Each type of enzyme can usually catalyse only one type of reaction (some may catalyse a few types of reactions).
how does temperature affect enzymes
An enzyme willl have an optimal temperature. A higher temp will usually increase the rate of reaction at first but if It gets too hot the bonds holding the enzymes together break. This changes the shape of the enzymes active site so the substrate won’t fit any more. also some of the bonds holding the enzyme together break.
the enzyme is said to be denatured.
how does ph affect enzymes
the ph interferes with the bonds holding the enzyme together this changes the shape of the active site and denatures the enzyme.
what is genetic engineering
t his process involves moving a gene or genes from one species to another. This is a complicated scientific process which can improve crops and even make bacteria to make medicines like insulin.
how Is genetic engineering used to treat diabetes
Diabetes is a disorder in which the body’s blood glucose levels remain too high because glucose is not effectively removed from the blood. It can be treated by injecting insulin. The injected insulin acts just as natural insulin and causes glucose to be taken up by the liver and other tissues, which results in cells receiving the glucose they need, and blood glucose levels stay normal.
Bacterial cells have been genetically modified to produce substances such as human insulin.
how can an antibiotic be resisted against
A bacteria can develop random mutations within their DNA and these can create new alleles which change the bacterias characteristics eg. bacterium can be less affected by a certain antibiotic.
For the bacteria this gives it a big advantage as it is more likely to survive and therefore it can reproduce more.
How do pregnancy tests work
They detect a hormone that is only produced in pregnant women the hormone is present in tiny amounts so they have to be sensitive
They need large amounts of identical antibodies called monoclonal antibodies
