University Of Regina Biology 140 Final (Laura Ambrose)

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Allelle

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Different forms of a gene (ex. trait = eye colour, alleles = brown and blue)

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Inheritance

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The study of how genes are passed from one generation to the next

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Genotype

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The genes that a person has includes all the genes a person has and the alleles a person has for a trait

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Phenotype

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The traits a person has.

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Trait

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Something you can see or measure like eye colour

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Homozygous

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if the genes in a pair of homologous chromosomes are the same. homo - same, zygous - pair

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Heterozygous

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If the genes in a pair of homologous chromosomes are different. hetero - different

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Dominant

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An allele that is expressed in the presence of a different allele

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Recessive

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An allele that is only expressed when there are two copies that are the same

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Homozygous dominant

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Dominant, Dominant = AA

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Heterozygous (carrier)

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Dominant, Recessive = Aa

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Homozygous recessive

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Recessive, recessive = aa

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Carrier

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A heterozygous genotype means that the individual is a carrier of the recessive allele, even though the dominant allele will be expressed.

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One-trait cross

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Tracks one trait at a time.

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Two-trait cross

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Crossing individuals and tracking two traits at a time.

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polygenic

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poly - many, genic - genes. Traits are determined by many pairs of genes. These genes do not have to be on the same autosomal chromosome pair. Combination of different dominant alleles is additive - more dominant alleles = more product (Skin pigmentation)

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multifactorial inheritance

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multi - many, factorial - factors. Polygenic traits that are influenced by outside factors. Example several gene pairs determine the height trait of a person but it is influenced by environmental factors and nutrition during early development.

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Incomplete dominance

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When the dominant allele is not completely dominant over the recessive allele then the recessive allele is partailly expressed in a heterozygous pair.Blending occurs between the dominant and recessive phenotype (Ex. curly, wavy intermediary, straight hair) (Ex. Snapdragons can be coloured red, pick intermediary, or white)

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Co-dominance

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When there is more than one dominant allele can be expressed in a gene pair. If two dominant alleles are expressed it is a unique phenotype. (Blood type example)

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Multiple allele inheritance

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More than two kinds of genes. Each person receives two alleles for the trait.

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Sex-linked traits

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Genes carried on the sex chromosomes (Usually X as it is longer and contains more genetic information than the Y chromosome). Female XX and Male XY act as homologous pairs during meiosis 1 but no crossing over occurs. Female can be a carrier, male can not be.

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Understand and be able to explain how sickle cell disease is an example of an autosomal recessive disorder and
an incompletely dominant disorder

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Sickle cell disease is an autosomal recessive disorder meaning that the genes are on non-sex chromosomes (autosomes) homologous pairs. The allele that determines normal hemoglobin is dominant over the recessive allele that determines if a person has SCD. In order for a person to have sickle cell disease, two of the same alleles must be expressed. HOwever, this disorder is also incompletely dominant, meaning that the recessie trait is partially expresseeed in a heterozygous pair. This means that homozygous dominant person will have 100% normal hemoglobin, heterozygous will have 50% normal, and homozygous recessive will have 0%.

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why sickle cell disease still persists in some populations in the world

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SCD still persists in some parts of the world where malaria is prevalent. If the malaria virus enters a blood cell with SCD, the cell will sickle the infected cell and remove it. Therefore it is advantageous in these situations to have SCD. Individuals that are carriers for SCD will survive and reproduce better in these environments because they have good red blood cells but also have some sickle cells to protect against the malaria virus.

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Huntington's Disease

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Is the progressive degeneration of brain cells. It is caused by an abnormal version of the Huntington protein. IN normal function. In the gene, a base segment of CAG is supposed to repeat 10-25 times. In the abnormal version of the protein, CAG repeats > 35 times. Abnormal protein clumps disrupt neuron function. The reason that HD still exists in the population is that it is not expressed until later on in life after the faulty genes are passed to the next generation.

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Explain the four types of changes in chromosome structiure

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Can be caused by radiation, organic chemicals, or viruses.
1) Deletion: end breaks off, piece of middle lost of chromosome makes it shorter than the homologue
2)Duplication: Segment of the chromosome is repeated, affected chromosome is longer than homologue
3)Inversion: a segment of chromosome is

4)Translocation: a segment of chromosome is moved to another non-homologous chromosome

inverted, causing a reverse segment of genes

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Differentiation

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Development of cells so that they can carry out their function. Less specialized cells become more specialized cell types. Cancer cells are not differentiated and have no function in the body.

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Abnormal Chromosome function

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Regular cells have ways of stopping cellular replication. They do not copy the end piece of a chromosome and each time the cell replicates it copies one less gene. Finally it gets so that replication can't occur and the cell attempts to repair, if repair can't be done, then the cell is chromosome is marked for apoptosis where it is deleted. Cancer cells do not have this normal function and instead copy the chromosome to the end each time allowing for unlimited replication.

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Abnormal Chromosome structure

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Cancer cells have abnormally large nuclei that have unusually number of chromosomes that have unusual structure. Normal cell tries to repair abnormal chromosomes, if it can't be repaired it is marked for apoptosis

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Apoptosis

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If a chromosome has an abnormal structure it is tagged for deletion.

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Contact inhibition

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Normal cells practice contact inhibition and stop dividing once they contact each other. Cancer cells do not and instead pile up forming a tumour

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Benign tumor

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Collection of almost normal cells surrounded by a membrane. May have no impact on body function unless it interrupts organs & systems

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In Situ tumour

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Collection of almost normal cells, not surrounded by membrane occurs at the original site of cell mutation. May or may not disrupt body function.

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Malignant tumour

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Cells that can and have metastasized or spread from the original site of cell mutation

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Stimulating growth factor

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Factors that initiate cell division. Cancer cells will divide even in the absence of stimulating growth factors.

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Inhibiting growth factor

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Factor that inhibits or halts cell division. Cancer cells will continue to divide even in the presence of inhibiting growth factors

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Angiogenesis

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Angio(blood), Genesis(creation). Cells require a constant amount of oxygen and nutrients and must expel waste. As cancer tumour increased in size cells at centre die because O2 and nutrients can't diffuse fast enough. Tumour activates genes that produce new blood vessels. Nutrients and oxygen is diverted form healthy tissue to the tumour.

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Tumor Progression

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Initiation - A cell in tissue is exposed to something that mutates the DNA controlling cell division. DNA stops functioning and cell has the ability to divide continuously

Promotion - More mutations in the DNA that controls cell cycle and cell division. cElls acquire ability to pile up (no contact inhibition). The tumour forms in the place of first mutation occurrence. (in situ tumour)

Progression - Further mutations in dominant aggressive cell of the tumour. Gains the ability to move from original tumour sites. (Digest through healthy tissue into vessel, move around body, drill out of vessel into new tissue). This forms an invasive tumour. Aggressive divides to form a tumour of cells with the ability to move from the original site. Metastasis - Cancer cells move from original site. Tumor is malignant. Malignant cells produce digestive enzymes that are released from the cell. Surrounding tissue is digested. Malignant cells move through tissue until they reach lymphatic or cardiovascular vessels. Malignant cells transported around body. Drills out of vessel and starts new malignant tumour.

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mutagen

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Causes mutation in DNA but does not necessarily lead to cancer

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carcinogen

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mutagen that directly causes cancer

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c. Explain how radiation, organic chemicals, pollutants, and viruses cause cancer.

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Radiation - energy like X-ray, naturally occuring radon gas and nucleur energy that cause a mutation in the DNA and form cancer. Radon gas is the natural breakdown of uranium in soil, rock and water and in combination with smoking gives higher chance of lung cancer.

Organic Chemicals - like tobacco products that contain mutagens and carcinogens. Amount smoked and age which people started effect cancer risk. Environment tobacco smoke can cause cancer in oral throat, esophagus, pancreas, bladder, kidneys, cervix, lungs and combined with consistent alcohol use increases chance of cancer.

Pollutants - metals, dust and chemicals that end up in the body that we wouldn't normally want in or on body. Exmaples are asbestos used to insulate commerciial buildings and when disturbed causes health problems, cancer and respiratory issues and pesticides (2, 4-D) that are mutagenic and carcinogenic but commonly used by non-professionals

virus - infects host cells. The viral DNA is incorporated into the host genome for example hepatitis B causing liver cancer and human papilomavirus (HPV) is an STI that is linked to cervical cancer.

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autotransplantation

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auto(self). When using chemotherapy drugs, they target cells that rapidly divide (A main characteristic of cancer cells is rapid division). Now, in the bone marrow of your femur, red blood cells are produced meaning that there is a lot of rapid cell division in this area. Chemo drugs have a negative impact on red blood cell production so cancer patients have a hard time recovering after chemo. So before chemo begins, generic cells that will develop into blood cells are harvested from the bone marrow and stored. Then after chemo, these cells are transplanted back into the patient's bone marrow. This reduces the need to find a donor match and also protects against rejection and the need to use rejection medication.

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immunotherapy

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Newly developed cancer treatment that is a vaccine for specific types of cancer. Works by exposing the body to a molecule that would be produced by the cancer cells. Immune system remembers the molecule as something foreign so that if the foreign molecule is introduced into the system later by a cancer cell the immune system is able to attack the cancer cell. ex) Immunization for melanoma

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p53 gene therapy

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p53 is a gene that causes apoptosis. Advanced cancer cells (after many mutations) do not have a p53 gene. So the cancer cells cannot be destroyed by apoptosis. p53 gene therapy takes a adenovirus and genetically modifies it so that it can only live in the cells without a functioning p53 gene (cancer cells). The host cell builds more adenoviruses and the viruses burst out of the cell destroying the host cancer cell. Some tumours have been treated with the virus and tumour size has been reduced.

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Anti-angiogenesis drugs

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Drugs that destroy newly formed blood vessels so that tumour cannot gain oxygen and nutrients to grow larger and are unable to mestatasize to other areas through newly formed vessels. Injected into tumour, these drugs cause tumour to shrink.

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individual

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a single member of a species

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population

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a group of individuals living in one location

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gene pool

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all the genes existing in a population

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interbreeding

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mixing of genes between different populations. These are previously unconnected populations that meet in one place and mate.