Biology 101 Final Exam Study Guide PDF

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The teacher for this class was Professor Kathrein....

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Biology 101 Test #5 Study Guide Ch. 15: Chromosomal Basis of Inheritance 1. The Chromosomal Theory of Inheritance says that genes have specific loci along chromosomes and that chromosomes undergo segregation and independent assortment a. Combines Mendel’s observations and structure of chromosomes 2. Thomas Hunt Morgan studied variations in the offspring phenotypes a. Wild type (+): most common phenotype, red eyes, dominant b. Mutant: alternatives to wild type, white eyes c. No females in F2 generation had white eyes i. White is recessive ii. White allele located on X Chromosome d. Conclusion: genes must be carried on specific chromosomes e. Genes on sex chromosomes exhibit unique inheritance patterns 3. Basis of Sex a. X and Y chromosomes  Y is smaller b. Short segments at Y ends are only homologous portions c. Sex determination 50/50 chance d. SRY gene on Y chromosome codes for testes i. Will not develop as male if SRY gene is missing e. Y chromosome  78 genes (Hemizygous) i. Few disorders passed from father to son f. X chromosome  1,100 genes i. Females only express phenotype for disorder if she is homozygous for the allele g. Compare how an X-linked disorder is inherited in males versus females. Give at least two examples of X-linked disorders. i. Males only need one copy of the recessive gene to display the phenotype. ii. Females need two copies. iii. Hemophilia, color blindness, Duchenne muscular dystrophy 4. X inactivation in females a. Women have one x chromosome that is inactivated b. Chromosome is randomly chosen  shut off  Barr body i. Inside nuclear envelope ii. Reactivates in ovary cells that give rise to eggs c. Genes are inactive because chromosome is highly condensed d. Mosaic of cells: X from father and X from mother e. Inactivation modifies DNA and histone proteins 5. Linked genes a. Do not sort independently b. Tend to be inherited together c. Located near each other on the same chromosome

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d. Genetic recombination: offspring with trait combinations not found in either P generation parent i. Physical basis  random orientation of homologous chromosomes at metaphase 1 of meiosis e. True or false: most offspring of a recombinant testcross are parental type. i. True (still look like the parental) Alterations in chromosome number/structure a. Nondisjunction: homologous chromosomes do not separate during meiosis I or sister chromatids do not separate during meiosis II i. If gamete is fertilized zygote will be aneuploidic b. Anueploidy (2n+1, 2n-1): one or more chromosomes are present in extra or deficient copies (monosomic vs trisomic) c. Polyploidy (2n, 4n): more than two complete sets of chromosomes in all somatic cells (more common in plants than in animals) d. Occur because homologous chromosomes (meiosis) or sister chromatids (mitosis) don’t separate properly e. Describe four different types of chromosomal mutations. i. Deletions: fragment is lost ii. Duplication: fragment is inserted into sister chromatid iii. Inversion: fragment is flipped iv. Translocation: fragment joined to a non-homologous chromosome Human disorders a. Down syndrome (trisomy 21)  1/830 children i. Extra chromosome ii. Frequency increases with age of mother b. Aneuploidy of sex chromosomes i. Extra X chromosome in males  Klinefeiter syndrome 1. Male sex organs but small testes and sterile ii. Extra X chromosome in females  Turner syndrome 1. Slightly taller than average, Sterile Genomic Imprinting: Variation in phenotype that is dependent on which parent passed on the allele for those traits a. Occurs during gamete formation b. Silences a particular allele c. Methyl group added to cytosine nucleotides of an allele d. Normal development requires embryonic cells to have exactly 1 copy of certain genes Inheritance of Organelle Genes a. *not all genes located in nucleus b. extranuclear genes or cytoplasmic genes c. organelles reproduce themselves and transmit genes to daughter organelles d. mitochondrial genes i. passed from cytoplasm of egg ii. products make up protein complexes of ETC and ATP synthase

iii. mitochondrial diseases affect nervous/muscles systems e. inheritance depends on precise replication of DNA

Ch. 16: The Molecular Basis of Inheritance 1. Transformation: change in genotype and phenotype due to assimilation of external DNA by a cell 2. Virus: little more than DNA enclosed by a protective protein coat (phages  bacteria eaters) 3. What was the main argument for proteins as the main carriers of genetic information? a. More amino acids than nucleotides b. Proteins are more complex  lead to complexity and diversity of life 4. Griffith and Hershey and Chase’s experiments. a. Griffith: evidence that viral DNA can program cells i. Used bacteriophage viruses to infect bacterial cells b. Hershey and Chase: radioactive Phosphorus and Sulfur i. Phosphorus: not present in proteins only in DNA ii. Sulfur: not in DNA only in protein iii. Only saw radioactivity in cells with P (DNA)  DNA is genetic makeup 5. Chargaff’s rules a. Base composition of DNA varies between species b. Nitrogenous bases i. Adenine ii. Thymine iii. Guanine iv. Cytosine c. A + T = C + G 6. Structural Model of DNA a. Franklin: x-crystallography of double helix b. Watson and Crick: double helical shape (rope ladder with rungs) i. Sugar and phosphates outside of helix (side ropes) ii. H bonds between bases, antiparallel nature iii. Purine and pyrimidine consistent with width of x-ray data (rungs) 7. Accepted model of DNA replication a. Strands are complementary  each stores info to construct its pair b. Semi conservative: daughter molecule had one old stand from parent and one newly made strand 8. What are origins of replication? How do they differ in prokaryotic and eukaryotic chromosomes? a. Specific sites within specific sequences where replication begins b. Replication bubble (fork): replication proceeds in both directions c. Prok: one big circular chromosome with one origin of replication d. Euk: multiple linear chromosomes with multiple origins of replication

Protein

Main Function

Helicase

Unwinds and twists DNA at replication fork Bind to newly separated DNA strands to prevent rejoining Breaks, swivels, and rejoins parental DNA ahead of replication fork Creates RNA primer that is complementary to template strand Catalyzes the synthesis of new DNA Seals okazaki fragments together Remove RNA primers and fills gaps with DNA bases

Single-stranded binding proteins (SSBPs) Topoisomerase

Primase DNA Polymerase III Ligase DNA Polymerase I

Which strand is it present on? both Both Unwound parental strand

Lagging Both Lagging Lagging

9. The leading strand is synthesized continuously, while the lagging strand is synthesized via small fragments of DNA. 10. Process of DNA mismatch repair. a. Enzymes detect mismatch, cut out the error, and fill in gap with correct nucleotides b. Can also repair damage that occurs with environmental changes

Ch. 17: From Genes to Proteins 1. “Central Dogma” of molecular biology? a. DNA  transcription  RNA  translation  Proteins 2. Protein synthesis from DNA a. DNA as template  produce single strand mRNA b. mRNA carries genetic information from nucleus to ribosomes for translation 3. Where does transcription occur in the cell? Translation? a. Transcription: nucleus b. Translation: ribosomes, cytoplasm 4. The coding strand is identical to the mRNA transcript. 5. Three main characteristics of the genetic code a. Unambiguous: one codon codes for only one amino acid b. Redundant: more than one codon used for most amino acids c. Universal: same code applies to all organisms 6. Start codon(s) and stop codon(s). a. Start: AUG (methyanine)

b. Stop: UAA, UAG, UGA (don’t code for amino acids) 7. Transcription occurs in the 5’  3’ direction. 8. Define the terms “upstream” and “downstream” in relation to the promoter. a. Upstream: before the promoter, opposite direction of transcription b. Downstream: after the promoter, direction of transcription 9. Summarize the three steps of eukaryotic transcription. a. Initiation: transcription initiation complex form i. RNA polymerase and transcription factors bind to promoter b. Elongation: RNA polymerase moves 3’  5’ (nucleotides always added to 3’ end) c. Termination: poly-adenylation signal in pre-mRNA molecule 10. How are primary mRNA transcripts processed after transcription? a. 5’ cap: modified G nucleotide b. 3’ tail: poly-A tail c. RNA splicing (introns are spliced out, exons are joined together) 11. Compare the functions of the three different types of RNA molecules. a. mRNA: carries genetic information from DNA b. rRNA: ribozymes that are integral prats of ribosomes c. tRNA: convert codons from mRNA into appropriate amino acids 12. What is the function of aminoacyl-tRNA synthetase? a. Links correct amino acids to correct tRNA 13. Summarize the three steps of eukaryotic translation. a. Initiation: initiation complex forms b. Elongation: Peptide bonds are forming between adjacent amino acids c. Termination: release factor binds to A site at stop codon 14. List three modes of post-translational modifications. a. Chaperone proteins: help proteins fold into functional tertiary state b. Protein degradation c. Common modification: attaching lipids/carbs to proteins s...