Podcast
Questions and Answers
Which of the following statements best describes a gene?
Which of the following statements best describes a gene?
An allele is a variation of a gene.
An allele is a variation of a gene.
True (A)
What is the physical location of a gene called?
What is the physical location of a gene called?
locus
DNA stands for __________.
DNA stands for __________.
Signup and view all the answers
Match the following characteristics of genetic material with their descriptions:
Match the following characteristics of genetic material with their descriptions:
Signup and view all the answers
What role do tRNAs play in translation?
What role do tRNAs play in translation?
Signup and view all the answers
Introns must be removed before translation to avoid producing a gibberish polypeptide.
Introns must be removed before translation to avoid producing a gibberish polypeptide.
Signup and view all the answers
What is the start codon typically used in protein synthesis?
What is the start codon typically used in protein synthesis?
Signup and view all the answers
The process of decoding mRNA to build a polypeptide is known as __________.
The process of decoding mRNA to build a polypeptide is known as __________.
Signup and view all the answers
Match the components involved in translation with their functions:
Match the components involved in translation with their functions:
Signup and view all the answers
What sugar is considered more stable than ribose sugar?
What sugar is considered more stable than ribose sugar?
Signup and view all the answers
Uracil is more energetically expensive to produce than thymine.
Uracil is more energetically expensive to produce than thymine.
Signup and view all the answers
Why is thymine used in DNA instead of uracil?
Why is thymine used in DNA instead of uracil?
Signup and view all the answers
The total amount of DNA present in the cells contributes to differences between _____.
The total amount of DNA present in the cells contributes to differences between _____.
Signup and view all the answers
Match the following types of cells with their characteristics:
Match the following types of cells with their characteristics:
Signup and view all the answers
What is true about UAA, UAG, and UGA codons?
What is true about UAA, UAG, and UGA codons?
Signup and view all the answers
The genetic code is only found in eukaryotic organisms.
The genetic code is only found in eukaryotic organisms.
Signup and view all the answers
What do we call the property of the genetic code where a single codon can code for more than one amino acid?
What do we call the property of the genetic code where a single codon can code for more than one amino acid?
Signup and view all the answers
The coding units or codons for amino acids comprise ______ letter words.
The coding units or codons for amino acids comprise ______ letter words.
Signup and view all the answers
Match the following properties of the genetic code with their definitions:
Match the following properties of the genetic code with their definitions:
Signup and view all the answers
What is the role of DNA helicase in DNA replication?
What is the role of DNA helicase in DNA replication?
Signup and view all the answers
DNA replication is a conservative process where the original DNA remains intact and a wholly new copy is made.
DNA replication is a conservative process where the original DNA remains intact and a wholly new copy is made.
Signup and view all the answers
What is the function of DNA polymerase in DNA replication?
What is the function of DNA polymerase in DNA replication?
Signup and view all the answers
The process of _____ leads to the formation of messenger RNA complementary to the DNA strand.
The process of _____ leads to the formation of messenger RNA complementary to the DNA strand.
Signup and view all the answers
Which enzyme stabilizes newly single-stranded regions during DNA replication?
Which enzyme stabilizes newly single-stranded regions during DNA replication?
Signup and view all the answers
Match the following processes with their descriptions:
Match the following processes with their descriptions:
Signup and view all the answers
Who are the scientists credited with the model of DNA?
Who are the scientists credited with the model of DNA?
Signup and view all the answers
The Central Dogma refers to the processes of DNA replication and mutation only.
The Central Dogma refers to the processes of DNA replication and mutation only.
Signup and view all the answers
What is the significance of base-pairing in DNA?
What is the significance of base-pairing in DNA?
Signup and view all the answers
The process by which genes are expressed is regulated by __________.
The process by which genes are expressed is regulated by __________.
Signup and view all the answers
Match the following concepts with their brief description:
Match the following concepts with their brief description:
Signup and view all the answers
Which of the following is NOT a property of the genetic code?
Which of the following is NOT a property of the genetic code?
Signup and view all the answers
Biomedical genetics focuses solely on the physical traits of organisms.
Biomedical genetics focuses solely on the physical traits of organisms.
Signup and view all the answers
Study Notes
Course Information
- Course title: Molecular Genetics
- Course code: ABCS 355
- Credit hours: 2 credits
- Instructor: Bethel Kwansa-Bentum, PhD
- Institution: University of Ghana
Course Outline
- Structure and function of DNA and RNA
- Regulation of gene transcription and expression of prokaryotes
- Mutations and concomitant altered proteins
- Behavioral genetics, prokaryotic gene expression, gene mapping, and biomedical genetics
Objectives
- Discuss the path to the Watson and Crick model of DNA
- Discuss the Watson and Crick model of DNA
- Explain the processes of the Central Dogma
- Discuss the properties of the Genetic code
- Discuss how cells regulate expression of genes
- Differentiate between Mutations and Polymorphisms
- Explain the roles of genes in biomedicine and organism behavior
- Outline the importance of gene mapping
References
- Griffiths et al. (2010). Introduction to genetic analysis, 10th edition. W. H. Freeman and Company, New York.
- Gurbachan (2015). Essentials of Molecular Genetics. Alpha Science International Ltd., Oxford, U.K.
- Klug and Cummings (2003). Concepts of genetics. Upper Saddle River, Prentice Hall, New Jersey.
- Russell (2000). Fundamentals of Genetics, 2nd edition. Addison Wesley Longman.
- Snustad, Simmons, and Jenkins (1997). Principles of Genetics. John Wiley and Sons Inc. New York.
- Strachan and Read (2010). Human Molecular Genetics. 4th Edition. Garland Science, U.S.A.
Course Delivery Schedule (2021)
- Week 1 (April 6th): Path to the Watson and Crick model (contributions of scientists to understanding DNA)
- Week 2 (April 13th): Watson and Crick model of DNA, RNA structure (distinguishing nucleoside/nucleotide, DNA vs. RNA, significance of base-pairing)
- Week 3 (April 20th): The Central dogma (DNA replication, transcription, translation)
- Week 4 (April 27th): The Genetic Code (properties of the genetic code, types of mutations, types of polymorphisms)
- Week 5 (May 4th): Behavioral genetics, prokaryotic gene expression (significance of gene regulation, operon)
- Week 6 (May 11th): Gene mapping, biomedical genetics
The Path to Watson and Crick Model
- Early scientists' contributions to understanding DNA
Section Objectives (Page 7)
- Gene definition at the molecular level
- Scientists' contributions to understanding DNA's nature
Gene – The Unit of Heredity
- Genes are organized within chromosomes
- Locus is the physical location of a gene
- Alleles are different versions of a gene (e.g., blue/brown eye color allele)
- Genes determine almost all traits in an organism
- Genes consist of DNA
Characteristics of Genetic Material
- Information repository for the cell
- Transfer of information on demand
- Faithful replication to pass information across generations
- Stability to withstand mutations
Griffith's Transformation Experiment (1928)
- First experiment on gene transfer
- Used S-strain (lethal) and R-strain (non-lethal) bacteria.
- Heat-killed S-strain alone did not cause infection.
Avery, MacLeod, McCarty (1944)
- DNA, not proteins, can transform genetic properties.
- Used radioactive phosphorus to label DNA.
Hershey and Chase (1952)
- Definitive proof that DNA is the genetic material.
Rosalind Franklin (1952)
- X-ray diffraction images provided crucial insights into DNA structure, leading to the understanding of DNA's helical nature.
Summary (Page 14)
- Miescher's DNA identification
- Griffith's gene transfer experiment
- Avery, MacLeod, McCarty's demonstration of DNA's role in transformation.
- Hershey-Chase confirmation that DNA is genetic material.
- Franklin's x-ray diffraction images
- Watson & Crick's DNA structure model
Watson and Crick Model of DNA Structure (Page 15)
Objectives (Page 16)
- Distinguishing nucleoside/nucleotide
- Importance of nucleotide components
- Describing nucleotide linkages within chains
- Detailing base pairing importance
- Differentiating DNA/RNA structures
- Analyzing factors causing differences between species, individuals and cells.
Nucleotide
- Consists of a nitrogenous base, deoxyribose sugar, and a phosphate group.
The 5 Nitrogenous Bases
- Purines (guanine, adenine): two rings
- Pyrimidines (cytosine, thymine, uracil): one ring
The 4 Nitrogenous Bases in DNA (Page 19)
- DNA structure's backbone is of repeating sugar and phosphate residues connected by phosphodiester bonds.
- Bases attract each other via hydrogen-bonds.
- Phosphate groups are negatively charged, which enhances solubility in water.
The Double Helix (Page 20)
- DNA structure is a double helix made of two anti-parallel strands
- Nucleotide pairs are joined together by hydrogen bonds to form the "rungs" of the DNA "ladder".
- The two strands are antiparallel
The Two Strands are Complementary (Page 21)
- Adenine bonds with Thymine (2 Hydrogen bonds)
- Guanine bonds with Cytosine (3 Hydrogen bonds)
- Base pairing allows DNA to replicate itself
The Two Strands are Antiparallel (Page 22)
- The strands run in opposite directions (5' to 3' and 3' to 5')
Structure of DNA (Page 23)
- DNA is composed of two polynucleotide chains forming a double helix.
- Carries genetic instructions for the growth, development, functioning, and reproduction of known organisms.
- Each turn of the helix contains about 10.4 nucleotide pairs.
Erwin Chargaff's Rule (1950) (Pages 24-25)
- Number of purines equals the number of pyrimidines
- Adenine to thymine ratio and guanine to cytosine ratio are close to 1:1
- AT/GC ratio varies between species.
Differences Between Species (Pages 35-36)
- DNA percentages do not specify species differences.
- Vastly differing genome sizes can have similar nucleotide percentages
- Differences in species originate from variations in base sequence and total DNA present.
Differences Between Individuals of the Same Species (Page 38)
- Total DNA amount is roughly similar for individuals of the same species
- Variations in base sequence
Differences Between Cells of the Same Individual (Page 39)
- Differences in how genes are expressed
- Different genes and active gene sets found in various cell types
Differences Between Normal and Cancerous Cells (Page 40)
- Chromosome alterations are common in cancerous cells
- Cancer cells are often aneuploid (altered chromosome number)
Central Dogma of Biology (Page 41)
- Explains the flow of genetic information from DNA to RNA to protein
- Process of DNA replication, DNA transcription to RNA and RNA translation to protein.
- All 3 stages (replication, transcription, and translation) contain initiation, elongation, and termination steps each.
Replication (Pages 44-53)
- DNA replication is semi-conservative.
- Double-stranded DNA molecule gets copied to form two identical DNA molecules.
- Initiation steps: establishing replication origins, unwinding the DNA helix via helicase, stabilizing the single-stranded areas via single-strand binding proteins, and preventing supercoiling via DNA gyrase (in prokaryotes) or type II Topoisomerase (in eukaryotes)
- Initiation steps: RNA primer synthesis via primase for DNA polymerase which then extends the template DNA.
- Elongation steps: continuous synthesis on the leading strand, discontinuous synthesis to create Okazaki fragments on the lagging strand.
- Termination steps: process of expanding new DNA strands, ends of replication. Stabilization of newly synthesized DNA strands, removal of RNA primers via RNase H and connection of fragments via ligase.
Transcription (Pages 54-60)
- Information in DNA is copied into a messenger RNA (mRNA).
- Gene is the sequence of DNA transcribed into RNA.
- DNA safely stores genetic material as a reference or template.
- mRNA is complementary to DNA template sequence but has Uracil replacing Thymine.
- Initiation steps: locating target gene, binding RNA polymerase to promoter site.
- Elongation steps: RNA polymerase reads template DNA strand and extends the growing mRNA strand.
- Termination steps: RNA polymerase reaches terminator sequence in DNA, detaching from DNA and releasing mRNA.
Eukaryotic RNA Modifications (Page 61-62)
- Pre-mRNA modification: addition of 5' cap and poly-A tail to 3' end.
- Splicing of pre-mRNA: removal of introns, connecting exons to form mature mRNA.
Translation (Pages 63-72)
- mRNA is decoded to build polypeptide/protein chains.
- Codons of mRNA are read from 5' to 3' by tRNA molecules.
- tRNA has an anticodon that matches the mRNA codon and carries the specific amino acid.
- Ribosomes are protein-RNA complexes where tRNA binds to mRNA and amino acids are linked to form polypeptide chains.
- Initiation steps: small ribosomal subunit attaches to mRNA, initiator tRNA carrying methionine binds to start codon.
- Elongation steps: matching tRNA binds to next codon in A site, peptide bond is formed, tRNA in P site moves to E site, new tRNA enters A site. Process continues until stop codon.
- Termination steps: stop codon reaches A site, release factor binds to stop codon, separating polypeptide and ribosome.
Processing (Page 74)
- Following translation, polypeptide chains may be chemically altered, folded into 3D structures.
- Some proteins require chaperones for folding, special amino acid sequences direct them to specific locations.
Summary of Transcription and Translation (Page 75)
- Transcription takes place in the nucleus, copying DNA's instructions into mRNA.
- Translation happens within ribosomes, interpreting the mRNA code to assemble protein molecules.
- tRNA and ribosomes (rRNA) are used to convert mRNA sequence into amino acid sequence.
The Genetic Code (Pages 76-87)
- Defines how genetic code letters in RNA (U, C, A, G) create codons for 20 amino acids.
- Each codon is a combination of three letters; 64 possible codons
- AUG codon is the start codon, specifying methionine, and initiating peptide synthesis.
- UAA, UAG, and UGA are the stop codons
- Genetic code properties: Universal, unambiguous, redundant, triplet, non-overlapping, comma-less, co-linear.
- One gene produces one polypeptide
Properties of the Genetic Code (Pages 82-87)
- The universal genetic code is consistent in all living organisms
- Each codon uniquely codes for a specific amino acid
- Most amino acids are coded for by multiple codons (redundant).
- Codons are triplets (three letters).
- Codons are non-overlapping.
- The genetic code is comma-less (no punctuation between codons), co-linear (gene sequence corresponds to the polypeptide sequence) and shows gene-polypeptide parity.
Mutations and Polymorphisms (Pages 89-105)
- Mutation: any change in DNA sequence from normal.
- Types of mutations:
- Point mutations (change in a single nucleotide): silent, nonsence, missense (conservative/non-conservative)
- Insertion (addition of nucleotides): can cause frameshift mutations
- Deletion (removal of nucleotides): frameshift mutations
- Inversion (reversal of DNA segment): can change protein function
- Translocation (transfer of genes): genes from one chromosome to another
- Duplication: multiple copies of chromosomal regions, increasing protein levels
Causes of Mutations (Pages 101-103)
- Spontaneous (errors in DNA replication, aberrant recombination/segregation, reactive metabolic products, transposable elements, depurination, deamination, tautomeric shift)
- Induced (physical agents like radiation; chemical agents like mutagens)
Polymorphisms (Page 104)
- Polymorphisms are variations in DNA sequences that are common in a population.
- Includes variations in blood type, sexual dimorphism, etc
- SNPs (single nucleotide polymorphisms) are common types of polymorphisms
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on genetic concepts and the translation process with this quiz. It covers definitions, functions, and key terms related to genes, alleles, and tRNA's role in protein synthesis. Perfect for students of genetics!
