Biology 1000 – Principles of Biology ( BioS 115 Core II: Genetics) Exam Study Guide 2024/2025

Biology 1000 – Principles of Biology ( BioS 115 Core II: Genetics) Exam Study Guide 2024/2025. Review discussion about Breast Cancer Breast Cancer (BRCA1 and BRCA2) c. Provides instructions for making a protein that acts as a tumor suppressor d. Prevents cells from growing and dividing e. Accounts for 30-40% of families with breast cancer cases Penetrance and BRCA a. Refers to the risk of developing breast and ovarian cancer b. A reliable estimate of penetrance is crucial for medical counseling Penn Risk II Model a. Predicts the probability that a person has the BRCA 1 or 2 mutant gene. b. Doesn’t predict the risk of having breast cancer Biology 1000 – Principles of Biology ( BioS 115 Core II: Genetics) Exam Study Guide BioS 115 Core II: Genetics Study Guide Page 2 of 13 3. Discuss examples of environmental influence on gene expression: i. Age of onset a. When the phenotype is age-dependent b. Example: pattern baldness c. Allele 9b: the dominant allele in males, recessive allele in females d. b+ allele is the wildtype and doesn’t cause balding e. Sex- influenced f. Huntington’s Disease: Autosomal dominant Expressed later in life Lethal gene ii. Sex-linked vs influenced vs limited Sex Limited: - Genes that are on autosomes that affect a particular phenotype that appears in one sex and not the other - Turn on or off - Differences between male and female - When it’s in one sex - Examples: milk production, facial hair, growing egg or sperm. Sex Influenced: - Genes on autosomes whose traits appear in both sexes, but the frequency is different. - Variations based on sex - Examples: pattern baldness, body/facial hair - Women are 3X more likely than men. - Top 10 causes of death in women 65 and younger - Genetic bias and tends to cluster in families Cleft Lip and Plate: - 2:1 ratio in males vs females - Surgery can correct - No determined cause Lupus: - Selena Gomez has it - 1:9 ratio in male vs female - Chronic autoimmune disease - During ages 15-44 - Women of color are 2-3 more times likely to develop it BioS 115 Core II: Genetics Study Guide Page 3 of 13 - No cure - No determined cause Sex Linked: - On X or Y chromosomes - Examples: Hemophilia on the X chromosome. iii. Temperature a. Some alleles are temperature-dependent Siamese cats: - tyrosine is heat-dependent - The extremities of cats are colder, so they have melanin production - The belly of the cats is warmer so there is no melanin production. Sex in Turtles: - 28.5 degrees C results in both females and males - 30 degrees C results in females - 25 degrees C results in males iv. Chemicals The microbiome is everything in or on us. What we eat affects our microbiome. It can lead to obesity or even autoimmune disease. Chapter 16  Know the basic differences between regulated genes and constitutive genes Regulated genes are genes whose activity is controlled in response to needs of organism. - They are only active when they are needed. Constitutive genes are genes whose products are essential to the growing and dividing cell. - They are always active - Essential to the gene - ALWAYS ON  Know four main types of gene categories Housekeeping Genes that are turned on in all cells at ALL times  Transcriptions and splicing factors BioS 115 Core II: Genetics Study Guide Page 4 of 13  Translation factors  Histones  DNA repair mechanisms Cell type specific Genes that are turned on in each cell that gives a cell its specialized properties  Neuron factors Developmental Genes specific to a certain state of growth and development  Eye development genes Inducible Genes that are not normally expressed but can be in response to external stimuli  Bacteria / lac operon  Know EVERYTHING about the lac operon, lol – there is a lot of information o Understand the importance of the lac operon, know that it’s role is to be turned on in the presence of lactose, in an effort to breakdown lactose to glucose for energy. - Usually in bacteria - Refers to lactose - Codes for genes that are involved in the metabolism of lactose - The lac operon in bacteria wants to metabolize lactose. It will break it down into simple sugars for its use as a carbon source. o What happens in the absence of lactose? o Know the regions of the lac operon  lacI promoter site – what does this do?  lacI gene – what does this produce?  Repressor – negatively controls the expression of the operon through binding  Know three structural genes and their roles (although, you do not need to know the role of the transacetylase) o B- Galactosidase (lacZ+) breaks down lactose into glucose and galactose catalyzes the isomerization of lactose to allolactose o Lactose permease (lacy+) Membrane protein that actively transports lactose into the cell o Transacetylase (lacA+) Transfers acetyl group from acetyl LOA to B- Galactosidase The function is NOT FULLY understood o Lac repressor