BIOLOGY 120 LECTURE Week 7 Flashcards
BIOLOGY 120 LECTURE Week 7 Flashcards Biol 120
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This 15 page Class Notes was uploaded by Michelle Noratel on Sunday October 16, 2016. The Class Notes belongs to Biol 120 at Towson University taught by Jennifer M Wenzel in Fall 2016. Since its upload, it has received 8 views. For similar materials see Principles of Biology in Biology at Towson University.
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Date Created: 10/16/16
"Epigenetics" Lecture Eight Flashcards Chromosomes are composed of chromatin, which is DNA wound around proteins called "histones" (go back to Lecture Five notes for more information (:). Histones are proteins associated with DNA. What is Gene Expression? Methylation of DNA and histones causes nucleosomes to pack tightly together. Transcription factors (proteins that facilitate gene expression) cannot bind the DNA, and genes are not expressed. Methylated DNA is not Nucleosomes are small portions of DNA wrapped around histones expressed Histone acetylation results in loose packing of nucleosomes. Transcription factors can bind the DNA and genes are expressed Acetylated DNA is expressed "Epigenetics" Lecture Eight Flashcards Methyl groups and acetyl groups are responsible for regulating which genes are expressed This means that these chemicals Gene Expression control gene activity and their presence or absence within in a cell or at a specific gene dictates what that cell doesthis influences "who" we are Our experiences shape our genesnot which genes we have, but where, Are our genes our fate? when, and how they are being expressed The study of phenotypic trait variations caused by external/environmental factors that switch genes on and off and affect how cells read genes These variations are NOT caused by changes in the DNA sequence What are Epigenetics? How are changes in gene expression due to external factors involved in: Appearance Behavior Cancer Psychological disorders Changes in our offspring "Chromosomal Abnormalities" Lecture Nine Flashcards What is Chromosomal A missing, extra, or irregular portion of chromosomal DNA Abnormality? Problems in the number of chromosomes (either too many or too little) Missing pieces of chromosomes (some pieces may be lost or rearranged) Translocations on chromosomes (a piece of a chromosome breaks off and reattaches The number and appearance of What is a Karyotype? chromosomes in the nucleus of a eukaryotic cell "Chromosomal Abnormalities" Lecture Nine Flashcards Problems in number of chromosomes So what are Trisomy 21 Trisomy 13 Chromosomal Kleinfelter Syndrome Turner Syndrome Abnormalities? XYY Chromosomal abnormalities result in various symptoms based upon the chromosome affected and how Problems in structure of chromosomes Deletion Duplication Inversion Translocation Each species has a specific number of Problems in number: chromosomes Nondisjunction If homologous chromosomes don't separate properly during cell division (nondisjunction), cells end up with incorrect numbers of chromosomes Aneuploidy : an abnormal number of chromosomes Monosomy : when an individual is missing a chromosome from a pair Trisomy, tetrasomy, . when an individual has more than two chromosomes of a pair "Chromosomal Abnormalities" Lecture Nine Flashcards What is Trisomy 21? Down Syndrome Occurs when individual has three copies of chromosome 21 Physical symptoms : spots on the eye, flattened facial profile, poor muscle tone, short statue, etc Cognitive symptoms : speech delay, intellectual disability, impulsivity, etc 1 in 700 births (1/ ) 700 Older women have a larger probability of having a child with Down Syndrome because (since a woman is born with all of the eggs that she will ever have) Patau Syndrome her eggs become older and What is Trisomy 13? Most lethal trisomy with median survival is 3 days many are miscarried Symptoms : severe mental deficiency, facial clefting, neurological and heart defects 1/ births 9500 Increased risk with mother's age "Chromosomal Abnormalities" Lecture Nine Flashcards What is XXY? Klinefelter Syndrome Genotype is male Phenotype can be male, female, or intersex Usually male 1500to 1000 male births Extra X could come from mother or father S y m p t o ms: sterility, less testosterone production leading to slightly feminized appearance in adolescence (less muscle tone, less body hair, gynecomastia) May have cognitive and physical delays "Chromosomal Abnormalities" Lecture Nine Flashcards XO Turner Syndrome Genotype and phenotype female Only 45 chromosomes 1/ female births 2500 Missing chromosome from mother or father Symptoms: short stature, webbed neck, broad chest, etc Some have difficulty with imagining objects in relation to each other, nonverbal memory and attention, sense of direction, manual dexterity, nonverbal learning and social skills "Chromosomal Abnormalities" Lecture Nine Flashcards 11000ale births XYY Usually no huge impact, most don't even know Males with XXY karyotype have an increased growth velocity from early childhood, with an average final height approximately 7cm (3" above expected height Problems in Typically occur due to errors in crossover Chromosomal Structure Deletion: prodcution of one or more copies of any piece of DNA Inversion: segment of a chromosome is reversed end to end Translocation: rearrangement of parts between nonhomologous chromosomes "Chromosomal Abnormalities" Lecture Nine Flashcards Literally "cat's cry" syndrome Deletion: Cri du chat Deletion on chromosome 5 Extent of deletion varies Syndrome Symptoms: intellectual disability and delayed development, small head size (microcephaly), low birth weight, and weak muscle tone 1/ 1/ 20,000 50,000irths From mother or father "Chromosomal Abnormalities" Lecture Nine Flashcards Genetic information at the q21.1 Duplication: position of chromosome 1 is duplicated 1q21.1 microduplication at least once May represent a number of symptoms, including; Autism Large head Learning disability Heart defects Seizures, etc Prevalence is unknown, but 1/ people 700 tested for 1q21.1 have it "Chromosomal Abnormalities" Lecture Nine Flashcards Inversion of chromosome 9 Inversion: inv(9)p12q13 inv(9)p12q13 Most common inversion Occurs in 2% of population Likely harmless Some controversial reports suggest it contributes to male infertility "Chromosomal Abnormalities" Lecture Nine Flashcards Translocation: Translocation Philadelphia chromosome Philadelphia Translocation of chromosome 9 and 22 Contributes to chronic myelogenous Chromosome leukemia (CML) Alteration in the DNA sequences Single Gene Mutations forming a single gene May be inherited or acquired through environmental exposure A mutated gene will not be able to produce the correct amino acid sequence, which may lead to problems (e.g., Huntington's Disease) "Chromosomal Abnormalities" Lecture Nine Flashcards So, what is Huntington's Brain disorder affecting ability to think, talk, and move Disease? Mutation in a gene on chromosome 4, which codes for the huntingtin protein Normally, this gene's DNA sequence contains "CAG" repeated again and again (usually 1020 times) People with Huntington's Disease have an abnormally high number of these CAG triplets (around 40+) The brain cells of Huntington's Disease patients accumulate clumps of protein that become toxic, resulting in cell death Some patients lose more than 25% of their brain cells before they die In order for a human to The correct number of chromosomes The chromosomes to have all of the be "right," "typical," correct genes The genes in the chromosomes to be in etc, it has to have... the correct order of their bases Protein Synthesis: Transcription and Translation Protein synthesis is a complex process made up of the 2 ▯processes transcription and translation. In this activity you will trace the steps that are involved in protein ▯synthesis. A. Transcription Protein synthesis begins with DNA in the nucleus. Transcri▯ption takes place in the nucleus of the cell. During transcription messenger RNA (mRNA) reads and copies ▯DNA's nucleotide sequence in the form of a complimentary RNA strand. Then the mRNA carries th▯e DNA's information in the form of codons to the ribosome. Codons are a 3 nucleotide sequence ▯in an mRNA strand. At the ribosome, amino acids will be assembled to form a polypeptide, which will become a protein. Remember, A/T(U in RNA) and C/G pairs! A/T are Below is a DNA sequence. Write the sequence of mRNA codons▯ that would result from the transcription of the DNA sequence. st raighter, C/G are curvy/circula r DNA: ACA ATA TAG CTT TTG ACG GGG AAC CCC ATT mRNA: ________________________________________________________ B. Translation Translation takes place on the ribosome. For translation, amino acids are gathered based on the mRNA codons. Amino acids bond together forming polypeptide chains, which wil▯l form proteins. Rewrite your mRNA sequence from part A. Using the amino acid▯s table, determine the sequence of amino acids based on your mRNA strand. Use hyphens (dashe▯s) to separate amino acids. mRNA: __________________________________________________________________________ Amino Acid Sequence: _______Cysteine - Histidine - Isoleucine - Glutamic acid____ ___________________________________________________________________________▯_____ Arginine - STOP ________________________________________________________________________________ Label the following diagram of Protein Synthesis. DNA mRNA protein mRNA ribosome Answer the following questions about Protein Synthesis. Part A The RNA strand leaves the nucleus, meets with a ribosome, and . 6 Define translation. instructs the cell how to build the protein for that gene -- The . decoding of an mRNA message into a polypeptide chain (protein) . 7 List all of the molecules in the process RNA strand, nucleus, ribosome, proteins, cytoplasm . 8 Translation takes place in the __________________________________▯_. Part B . 9 Define transcription. . for a certain gene is unwound and a complementary mRNA strand is pro duced . 10 List all of the molecules in the process transcription. DNA, mRNA . 11 Transcription takes place on the ________________________________▯____. General Question 12 What is the purpose of protein synthesis? create a polypeptide -- a protein made out of a chain of amino acids. This tells our body what it needs to do in order to express our genes an d make us who we are!
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