Genetics in Nutrition: Course BDTS 417

Genetics in Nutrition

• The lecture series is course BDTS 417
• The lecturer is Peter Nuro-Ameyaw
• Course Objectives*
• Illustrate the understanding of the genetic basis of disease
• Explain the basic concepts of genetics, including the nature of genes, mutations, the impact on phenotype, and modes of inheritance
• Analyze and evaluate the likely effects of a person's genetic trait on their metabolic and physiologic function
• Assess how bioactive food components modulate gene expression
• Explain the basic concept of the metabolome in relation to nutrient intake

Course outline

• The course covers nucleotide chemistry, the flow of genetic information, genome and chromosome mutations, Mendelian defects, single-gene defects with non-classic inheritance, and antioxidants
• Week one focuses on nucleotide chemistry, including the double helix and nucleotide components such as base, phosphate, and sugar
• Weeks two and three delve into the flow of genetic information, covering DNA replication, transcription, and translation
• This section includes how antibiotics affect gene expression, DNA repair mechanisms, diseases associated with defective repair, and mutagenic agents
• Week four covers genome and chromosome mutations, focusing on the mechanisms and effects of numerical and structural chromosomal aberrations
• Week five explains Mendelian defects and single-gene defects with non-classic inheritance, including mechanisms, effects, and modes of inheritance
• Weeks six and seven are dedicated to antioxidants, discussing the antioxidant enzyme system, nutrient antioxidants and their dietary sources, and the importance of antioxidants
• This section covers free radicals, reactive oxygen species, their sources and generation, cellular metabolism, environmental effects, and harmful effects
• It also addresses free radicals and diseases, including cardiovascular diseases, cancer, respiratory diseases, and the aging process

Genetics in Nutrition Introduction

• Genetics explains certain conditions, such as lactose intolerance and celiac disease

Basic Terminologies

• Genetics is the study of genes, heredity, and variation in living organisms
• Heredity is the transmission of genetic information from parents to offspring, which maintains species constancy across generations
• Variation refers to differences in genetic traits among individuals or populations, caused by genetic mutations, recombination, and environmental factors
• A gene is a fundamental unit of heredity made up of DNA
• It comprises an ordered sequence of nucleotides located at a particular position on a chromosome and encodes a specific function
• A chromosome is a self-replicating genetic structure in cells containing DNA
• It bears in its nucleotide sequence the linear array of genes and is composed of tightly coiled DNA organized into a double-helix structure
• Chromosomes carry the genetic code and have proteins called histones that help package and organize the DNA
• DNA wraps around histones to form chromatin, which is further condensed

DNA

• DNA (Deoxyribonucleic Acid) is the molecule that carries genetic information, organized into structures called chromosomes
• Each organism has unique DNA, similar to a fingerprint

Nucleotide Chemistry: DNA Summary

• DNA is found in the cells of most living things
• Some viruses, such as retroviruses, have RNA as their genetic material
• DNA contains all of the genetic information that differentiates one organism from another
• Each organism has unique DNA, like a fingerprint
• Most DNA molecules are double-stranded helices
• Eukaryotes, such as humans, have double-stranded DNA
• Some viruses have single-stranded DNA, like papillomaviruses
• A double-stranded DNA molecule consists of two long biopolymers composed of simpler units called nucleotides
• Each nucleotide is composed of a nucleobase
  • These are recorded using the letters G, A, T, and C
• A nucleotide is the monomeric unit of DNA
• DNA is the hereditary material in humans and almost all other organisms
• Nearly every cell in the body has the same DNA
  • The exception is red blood cells, lens fiber cells, and mature keratinocytes in the epidermis
• DNA is mainly located in the nucleus
• However, mitochondria also contain DNA, known as mitochondrial DNA (mtDNA)

Nucleotide Chemistry: History

• Friedrich Miescher isolated "nuclein" (DNA) in cells from pus in 1869, and it became known as nucleic acid after 1874
• Phoebus Levene discovered that DNA is made up of nucleotides and proposed the tetranucleotide hypothesis
• The hypothesis states that DNA consists of equal amounts of nucleotides
• Rosalind Franklin used X-ray crystallography to help visualize the structure of DNA
• James D. Watson and Francis Crick are credited as the originators of the double helix model

DNA Structure

• DNA contains deoxyribose and ribose sugars
• DNA also requires phosphates and sugar
• The nitrogenous bases consist of two groups
• Pyrimidines
• Purines
• Pyrimidines
• Have one 6-member ring: thymine and cytosine
• Purines
• Consists of a 6-member ring, fused to a 5-member ring: adenine and guanine
• Uracil is only found in ribonucleic acids
• Each spiral strand has a sugar-phosphate backbone and attached bases connected to a complementary strand by hydrogen bonding
• Bases adenine (A) pairs with thymine (T)
• Guanine (G) pairs with cytosine (C)
• Two chains do not have the same base composition, but the chains are complementary to each other
• If One chain is AGATGCTG then a complimentary chain is TCTACGAC
• The more GC bonds there are, the stringer the bonds.
• DNA meiting temperature is the temperature at which 50% of the double-stranded DNA (dsDNA) separates into single strands (denatures)
• The DNA double helix is a twisted latter like structure formed by two strands of nucleotides

DNA Structure

• There are about 10 nucleotides pairs per helical turn
• The strands are anti parallel
• Which means two polynucleotide strands run in opposite directions along the length the double helix

DNA Replication

• DNA replication is the production of identical copies of DNA
• Replication is essential for division
• DNA makes an exact copy of itself doing cell division
• This ensures that genetic information is passed to cells
• Enzyme: DNA ploymerase
• Replication involves multiple steps:
  • Initiation
  • Elongation
  • Termination

DNA Replication: Intitation

• Replication begins at origin of replication site of DNA (Ori)
• Eukaryotic DNA has multiple points for original application to accelerate the replication
• "Ori" are rich
• Helicases unwind and separate the double-stranded DNA at the Ori site forming a bubble wth two replication forks

DNA Replication: Elongation

• Enzyme "primase" attaches at the RNA primer as a specific location to start Replication -- A primer is short and It 20 bases) that serves a starter of synthesis -- DNA ploymerase needed for DNA replication cannot start replication on its own
• DNA polymerase enzyme (DNA Pol III) catalyze the synthesis of new DNA strands using the original DNA strands as templates
• DNA polymerases add nucleotides to the growing new strands in a 5' to 3' direction, complementary to the template strands
• Leading strand: RNA primers are first synthesized by primase.
• DMA polymerase synthesizes the leading strand continuously in the 5' to 3' direction as the replication fork opens
• Lagging strand: DNA is synthesized discontinuously in short fragments called Okazaki fragments (100-200 nucleotides long)
• RNA primers are first synthesized by primase and then DMA polymerase sythesizes the Okazaki- fragments

DNA Replication: Termination

• Exonucleases removes the RNA primers from BOTH stands of the DNA
• DMA polymerase filles in the gaps with DNA
• DNA ligase seals up the frants of DNA to form a continuous double strand
• It is described as semi-conservative
• Made up of one old conserve strand of DNA and one new one

Gene expression:

• Different organisms produce proteins that are all different
• Certain organisms have similar biochemical pathways
  • Example: glycolysis
• It is the process by which the information encoded in a gene is ased to produce a functional product
• Essential for the regulation of cellular functions

Gene structure

• There is one gene that has
• Promoter
• Coding Region
• Termination Sequence

Gene expression: Central Dogma of Molecular Biology

• Describes the flow of genetic information in a biological system
• Proposed by Francis Crick In 1958
• it states that genetic information follows a one way path

Steps in the Central Dogma

• Tranecription turns DNA into RNA
  • Specific gene in DNA l copied into messenger RNA (mRNA)
  • Carried oulbyan enzyme called RNA polymerase, whieh binds to the DNA at the start of the gene's coding region and synthesires an mRNA molosale byadding complementary RNA nucleotidea..

Steps in Transcription

• protein molecules called transcription factors also bind to DNA atthe promoter to regulate gene expression

Gene expression: Transcription

Transcription: -- The first step of gene expression.

• There is acomplementary bate paiting at done ln DNA replication, that uradil replaces thynine inte RMA molecule

RNA processing: Transcription

• RNA processing (in eukaryotes):

• Newly synthesized mRNA undergoes processing steps: -Capping

• Splkng

• Polysdenylation

• There aae modification

• Protects a from degradation facilitate is the nucleus to thecytoplasm.

• Capping; Addition of a modified guanine nucleotide

• Cap) to the Vend of the pre-mRNA molecule.

Splicing

• Removalofnon coding sequncos introna) from the mRNA mlsculs and jainng together of remaining coding sequenens (exons)
• Mediated by the Spliceosome Addition of a string of adenice nucleotides (the poly(A) tai) to the 2'nd of the pre mRNA molecule. Aal preter to the mRNA frum degraration andisirved in nstRNk stabiity and rariation

Types of RNA producéd:

mRNA Cmessenger RNA to Carries generic Instructions tRNA (transter RNA) leipein protein synthesis. rRNA (ribosomal RNA) Parl of ribosomes. 2. Translation (RNA- Protein) niRNA isresdby ribosomes loassomblo amine acids ino a protein. Each three nucleotidesequence (coden in MRNA corresponds to a Specificamine acide Keys Players. Ribosames, tKNA, arming asics

Translation: Some terminologies

• Anticodon: le a squance that e adjarent nuclerides icated on the INA Ihat painwathal complementary inree adacont nucleoudea codon lo designate a specilicarrire

TRANSLATION: SOME TREMINOLOGIES

• A condon is a sequence of three adjacent nueleosides in massenger RNA that determinates the position of amino acids during proteins synthesis
• Genetic code le a set of threeletler combirations of rucleridescalled codons saeh arwhich correspond to a specificarwing acids stop segal

Translation:The genetic Code

• It is the set of nles veed by living cells to trarslate information encoded within genetic natelal inte peras
• Occurs in hancoplasin
• MRNA macecule interacts with ribosones
• Genedic intanmatian aneded in the mRNA a dacted
• Araino scids are assembed into a pcly peptide diain acrding to the equence of codons Cepiats of neiesider the mRNA mecule Trared RNA (RNA) malocules bring spesic amines acids to the tiboscine, where they are added to the growing polypeptide chain

Posi Translational Medification

The marly synthesizer polpesinde chain may undere further meclicatons to bene a functional prcein These modification may include-

• Saling is a spedit three dimensanad structure
• clevage of specific amine and sequences
• ddion ol dheal groups such at Pheralation or clyesiation assodatog with ether proain subunits to a functional proein capler

Explore the genetic basis of disease, basic genetics concepts, and the impact of genetic traits on metabolic and physiologic function. Learn how bioactive food components modulate gene expression and understand the metabolome's role in nutrient intake. The series covers nucleotide chemistry, mutations, Mendelian defects, and antioxidants.