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69 Cards in this Set
- Front
- Back
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Genome |
The complete set of genes in an organism |
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Prokaryotic cells |
This means that it's before a nucleus so it doesn't have one. They also don't have other membrane bound organelle. The cells are between 0.5-5um big.Example of this is bacteria |
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Structures in a prokaryotic cell |
★- not always present Mesosomes Plasmid★ Circular DNA Capsules★ Ribosomes Mesosomes Plasmid★Circular DNACapsules★RibosomesPili★Flagellum ★Cytoplasm Cell wallPlasma membrane Pili★ Flagellum ★ Cytoplasm Cell wall Plasma membrane
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Plasma membrane |
Works the same as it does in a Eukaryotic. It controls the movement of substances into and out of cells. |
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Cell walls |
The cells wall prevents it from. Changing shapes and is made up of Murein |
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Pili★ |
Short hairs that help it it stick to other cells, can be used in transfer of genetic material |
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Capsule★ |
Made up of secreted slime that protects it from being attacked by other celld |
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Mesosomes |
It is an inward fold in the plasma membrane.Its Function is debated. Could be a site of respiration. But others believe it's not natural and is the effect of cells being prepared for electron microscope |
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Plasmid★ |
Small loop if DNA that is not with the circular DNA. They contain genes for antibiotic resistance and can be passed between prokaryotes |
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Circular DNA |
DNA is free flowing in the cytoplasm and is in a long coiled up strand with no histone protiens attached |
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Flagellum ★ |
Long hair like structures that rotates to make the cell move |
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Cytoplasm |
Same as eukaryotes but don't membrane bound organelles in. |
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Eukaryotic cells |
They have a few membrane bound organelles and has a nucleus and are bigger than prokaryotes. Certain features differ depending on weather it's animal or plant cells |
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Features of an animal cell |
Mitochondria Nucleus Nucleolus Nuclear envelope Rough endoplasmic reticulum Smooth endoplasmic reticulum Ribosomes Cell surface membrane Golgi apparatus Lysosome Centrioles |
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Nucleus,nucleolus,nuclear pore, nuclear envelope |
The nucleus controls cells activities and holds DNA. the nuclear pores allows substances in and out and the nucleolus makes ribosome |
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Lysomes |
Contains digestive enzymes and are separate until u need it |
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Ribosomes |
It is either free floating or attached to the rER where protien are made |
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Rough endoplasmic reticulum (RER) |
A system of membrane enclosing fluid filled space with ribosomes attached so it can fold and process protiens |
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Smooth endoplasmic reticulum (SER) |
A system of membrane enclosing fluid filled space with no ribosomes and this synthesises and processes lipids |
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Golgi apparatus |
A fluid filled membrane bound flattened sacs that process and packages new protiens and lipids and can make lysosomes. |
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Mitochondria |
Oval shaped double membrane with crista and matrix that help with aerobic respiration where ATP is produced. respiration where ATP is produced. |
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Centriole |
Hollow cylinders made of microtubules that separate chromosomes in cell division |
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How protiens are synthesised |
The Amino acid chain moves to the rough ER and it is moulded to its tertiary structure then the vesicle with the protien is pinched of from the rough ER and moves to the golgi apparatus and the vesicles with the protien fuse together to form the cis cisterna then moves along the flattened sacs and their a golgi enzymes that modifies the protien in the medial and then goes to the trans golgi network where they are organised into where it needs to be transported then buds of forming a vesicle to where it's needed. |
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Structures in an egg |
Haploid nucleus Cytoplasm Follicle cell(outermost layer) pellucida Cell surface membrane Zona pellucida Cell surface membrane Lipid droplet Lysomes |
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Structures in a sperm |
Acrosome Nucleus Mitochondrion Flagellum
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Fertilisation |
When the cervix is open during ovulation the sperms enters and tries to get to the oviduct where the egg is. Chemicals are released from the eggs to attract sperms. The sperm that's the fastest fuse with the follicle cells and the acrosome is released to digest the follicle cells and zona pellucida which is called the acrosome reaction. When this happens the egg has a corticle reaction that thickens the zona pellucida so other sperms can't get in and the sperm nucleus is inside the egg and fuses with its nucleus to be fertilised. |
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How gametes are formed? |
Through meiosis that produces a haploid cells that are different |
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Meiosis |
1) DNA replicates so there is two identical copies of each chrosomes 2)DNA condenses to form chromatids that are double armed 3) chromosome arrange them self into homologous pairs 4)First division homologous pairs are separated 5) Second division separates the sister chromotids |
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Independent assortment |
Different combinations of maternal and paternal chromosomes go into each cells |
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Crossing over |
Before division the homologous pairs of chromosomes pair and the two chromatids in each homologous pair twist around each others and bits break(chiasma) and join the other chromatids, leading to a different allele combination between non sister chromatids. |
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Linkage |
Positions of the gene on the chromosome effects how two factors are related...if they are closer together on the same Chromosome they will be linked but won't be linked if they are on separate chromosomes |
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Sex linkage |
All genes on the sex Chromosome are passed on with those that determine sex. |
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Cell cycle |
Interphase consist of G1 S G2 G1- Growth of cell S- synthesis of DNA G2-preparation of mitosis Interphase over Mitosis Cytokinesis |
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DNA structure change |
Starts of with the double helix that is wrapped around the histones which effects genre expression. The DNA and histone protiens coil to form a chromatin fibre. This attaches to a protien and scaffold form which then forms a condensed chromosome structure. |
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Prophase |
Chromosomes condense and form chromatids. The two strands are identical and are joined at the centromere.
The centrioles are at the opposite ends of the nuclear envelope and spindle fibres form and the nuclear envelope starts to break down. |
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Metaphase |
The spindle fibres attach to the centromeres and the chromosomes move to the equator |
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Anaphase |
The centromeres split the spindle fibres pull each half to their side. |
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Telophase |
The chromosomes unravel and a new nuclear envelope forms around each end leading to a new nuclei |
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Cytoplasmic division |
Cell surface membrane constricts around the centre of the cell and protien filaments are bounded to the inside surface of the cell.they contract until the cell divided into two new cells. |
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Importance of mitosis |
Growth and repair - ensures multicellular organisms have genetic consistency. Can regenerate lost or damaged parts of the body
Helps Asexual reproduction |
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Totipotent stem cells |
They can develop into any cell and are formed when the human zygote undergoes all the cell cycle. |
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Blastocyst |
This is a hollow ball of cells formed after 5 days of conception and the outer layers goes on to become the placenta. The inner cell forms the tissue of the developing embryo. |
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Pluripotent cells |
Potentially form most cell types,but not all. Start of being unspecialised |
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Multipotent |
Adult cells that can form another cell. Ie bone marrow can become blood cells |
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Human stem cells in medicine |
Embryonic stem cells can be used to have pluripotent cells and the blastocyst from ivf could also lead replacing damaged organs. However it can still be rejected by ur body |
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Therapeutive cloning |
A diploid cell is removed from their body and the nucleus would fuse with an oval with its haploid nucleus removed. This is then stimulated to divide by mitosis in the same way as normal cloning.but when the blastocyst is formed the stem cells are isolated and encouraged to develop into the needed tissue. |
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Reprogramming somatic cells |
You can use a body cell and reprogramming it to be pluripotent. They are induced pluripotent cells. This is only tested on mouse and tissue cultures. |
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Ethical issues |
No problem in using adult stem cells but pluripotent stem cells from the embryo is seen as unethical because some see it as human life so it's harmed. |
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Proof of the nucleus containing genetic information |
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Gene expression - How stem cells become specialised ? |
All stem cells have the same genome but they are not all expressed. Depending on the condition the cell is leads to certain genes being active and inactive. mRNA only transcribes active genes to protien and those protiens modify and differentaite the cell for its purpose. The cell then stays specialised. |
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Transcription factors on Eukaryotes |
Protiens bind to DNA to activate or deactivate genes by increasing or decreasing transcription. The specific DNA site is targeted thar control gene expression
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How prokaryotes can control gene expression |
They have operon's which contains clusters of structural genes that are transcribed together as well as control elements. These work with repressors or activators that help gene expression. Activators can help the operon bind to DNA sometimes if needed Repressors block the DNA strand. |
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Lac operon in E coli |
The lac operon can code for enzymes ( beta glactosidase,lactose permase) that help E.coli respire.
If Lactose is not present the Operon won't work because the lac repressors bind to the operator site which block the operon therefore the enzyme is not transcribed
If Lactose is present it binds to the lac repressors which stops it binding to the operator so the operon can now transcribe the enzyme |
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Role of epigenome in gene expression |
Chemical markers is known as the epigenome. The attachment of certain chemicals like a methyl group prevent transcription of that gene because RNA polymerase can't bind. The modification of how tightly histones is wrapped around the DNA is due to chemical markers and if it is tight the genes are inactive. |
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Switching on genes in an Eukaryotic |
Genes uncoil and accessible regions can be transcribed into mRNA. DNA polymerase bind to the section of DNA adjacent to be transcribed know as the promoter region. It can only attach with a regulatory protien. |
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Tissues |
Specialised cells group them self into clusters and they have recognition protiens that help adhesion between the cells that bind them together. |
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Master gene |
Controls development of each segment. Produces mRNA that is translated into signal protiens. |
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Discontinuous variation |
When the environment has no effect on the gene and there are discrete groups. |
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Continous variation |
When there are effected by genotype and environment they show a more of a range and are controlled by the loci of genes. |
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Polygenic inheritance |
Number of genes involved in the inheritance of a characteristic. This can lead a to susceptibility to the condition with the environment. |
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Environmental factors helping height |
Less inbreeding Better nutrition and more protein Better health End of child labour Better heating so less energy need for other processes |
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Making melanin |
Melanin is formed from melanocytes in your skin or hair follicles that are activates by melanocytes stimulating hormones. Melanocytes have receptors that collect the hormone which places them into an organelle called melanosomes which is transferred to nearby cells and collect around the nucleus as a barrier to UV light. The more melanin the darker skin is. Hair get lighter Because UV light destroys melanin |
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How melanin is formed in some animals |
An enzyme called tyrosinase catalysed the chemical step of Amino acids tyrosine into melanin |
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Environmental effect on epigenome |
Factors such as drug and diet can make changes in the epigenome at early develop which effects the phenotype |
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Behaviors effecting the epigenome |
Certain behaviors in animals changed the some epigenome that lead to certain characteristics. In rats when a mother grooms and licks their offspring no methylation of GR gene in offspring so it is expressed but there is methylation of GR gene if there is no licking and grooning |
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Cancer |
Rate of cell multiplication is faster than rate of cell death which leads to tumour. |
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Cause of cancer |
Damage to the DNA from UV light or asbestos or carcinogenic or mutations. This cause abnormal methylation in DNA that activate or deactivate genes controlling the cell cycle Less methylation in Involved leads to the cell cycle being continuously active so there is excessive cell division Too much methylation in the tumour repressor genes means it can stop the cell cycle |
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Inherited cancer |
Some cancers can be inherited because gene defects can be inherited which makes the patient susceptible to cancer. |
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Environment and cancer |
Smoking increase likelihood of cancer because tar is carcinogenic and cause damage to the DNA in epithelial cells. UV light physically damaged DNA in ur skin cells Radical chemical from diet can damage ur DNA Virus infections |
