Untitled Quiz

Unit V: Nucleic Acids

• The unit focuses on nucleic acids, specifically DNA and RNA.

Lesson Objectives

• Describe the molecular structure of DNA and RNA, including their components.
• Explain the processes of replication, transcription, and translation, and how genetic information is transferred from DNA to RNA to protein.
• Demonstrate understanding of how nucleic acids regulate gene expression, including the role of promoters, enhancers, and transcription factors.
• Explain the potential impact on protein function and organismal traits.

Differentiate a Gene from DNA

• A gene is a segment of DNA.
• DNA carries the genetic instructions (hereditary material).
• Genes can be replicated or copied.
• Genes are like a series of letters strung together (with proteins).
• Genes are like an instruction book.

What is a Chromosome?

• Chromosomes are long strands of DNA.
• Humans have 46 chromosomes.
• Paired chromosomes (autosomes) are numbered 1 to 22 based on size.
• The remaining two chromosomes are the sex chromosomes (X and Y).

Genetics: Gregor Mendel

• Gregor Mendel was an Austrian monk considered the "Father of Genetics";
• He was born in the Czech Republic.
• He studied genes and heredity using pea plants (Pisum sativum).
• Pea plants have many varieties that produce faster.
• He worked out the basic laws of inheritance through experiments with pea plants.

Traits of Pea Plants

• Seed form (round or wrinkled)
• Seed color (yellow or green)
• Flower color (white or violet)
• Pod form (full or constricted)
• Pod color (green or yellow)
• Stem size (tall or short)

Differentiate a Nucleic Acid from a Nucleotide

• A nucleotide is a building block of nucleic acids (DNA and RNA).
• Nucleotides have a five-carbon sugar backbone, a phosphate group, and nitrogen bases.

What is a Nucleotide?

• A nucleotide is made of three main parts: a five-carbon sugar, a phosphate group, and a nitrogenous base.
• DNA and RNA are polymers made of nucleotides.

What is a Nucleoside?

• A nucleoside is a structural subunit of nucleic acids.
• It can be a pyrimidine or purine.
• Nucleic acids contain nucleosides.

Heredity

• Heredity is the transmission of traits from one generation to the next.
• Genetic heritage is passed down from parents.
• Traits are determined by genes.
• A single gene can have variants (alleles).

How does Heredity Work?

• Genes encode instructions for making proteins.
• Genetic information is transferred to offspring.
• In sexual reproduction, each cell contains two variants of each chromosome, one from each parent.
• Variations arise from new combinations of chromosomes in offspring.
• Mutations can also cause variations.
• Mutations might be harmful, neutral, or beneficial to an individual.

When Mutation Affects a Gene

• When a mutation affects a gene, there may be a genetic disorder.
• These terms describe the effects:
  • Disease: A unique process in the body with specific causes and symptoms.
  • Disorder: A disruption to normal functions.
  • Syndrome: A set of symptoms that appear together, characterizing a specific disease.

Relationship of Proteins and Nucleic Acids

• Nucleic acids (DNA) encode the information necessary to build proteins.
• The central dogma of molecular biology explains the flow of information from DNA to RNA to protein.

Protein Synthesis (Transcription and Translation)

• Protein synthesis is the process where a sequence of DNA is used to build a protein from individual amino acids.
• Transcription is the start of the process where a coding region of DNA is converted to messenger RNA (mRNA). mRNA carries instructions from the DNA sequence out of the nucleus and to ribosomes in cells' cytoplasm.
• During transcription, mRNA is made from the DNA sequence following base pairing rules where uracil replaces thymine.
• The ribosome reads the mRNA three bases (codons) at a time.
• Each codon specifies an amino acid. These amino acids join to form a protein, a process called translation.

Codon Wheel

• Codons are used to signal the beginning of protein synthesis (START codon).

• There are three codons that signal the end of protein synthesis (STOP codons).

Codon Chart

• The codon chart shows the correspondence between codons that carry the genetic code and the amino acids specified by the codons.

Gene Expression

• Gene expression is the process where information from a gene is used to build a functional product, often a protein.
• Gene expression happens through the transcription of RNA molecules.
• These RNA molecules can either code for proteins or have other functions.
• A gene that encodes a polypeptide is expressed in two steps using the central dogma of molecular biology.

• Gene expression can be studied 'classically' through observing the phenotype, a physical characteristic determined by the protein's function.
• Recent technology has advanced to enable the ability to measure mRNA expression across the entire genome.
• Constitutive genes encode proteins involved in basic metabolic processes and maintain stability. 

• Regulatory genes can turn 'on' or 'off' and are influenced by factors like environmental conditions. 


• In prokaryotes, regulatory proteins usually turn genes off and may require ligands attached for binding to a particular gene.
• In eukaryotes cell-cell differences are determined by expressiong of different genes.
• An example of gene differences showing 'classic' phenotypes is from an undifferentiated fertilized egg showing phenotypic differences from other cells like: skin, neuron, and muscle.

Epigenetic Clock Marks Age of Human Tissues and Cells

• Recent research has shown DNA changes can predict longevity.
• Epigenetic age better represents a biological age compared to chronological age.

Research Gap

• For years, scientists tried to measure aging by studying changes inside the cells, particularly DNA methylation.
• This area is important in the aging process and may also help determine potential therapeutic targets.

Research Problem

• Research examined the relationship between DNA methylation and aging.

Methodology

• Scientists developed an age predictor based on 353 specific DNA sites where methyl groups increased or decreased with age.

• Scientists analyzed nearly 6,000 samples from 20 different cancers.

Results

• Computed biological age in numerous tissues and cells was within a few years of chronological age, not in skeletal muscle, heat tissue, and breast tissue.

• Cancer greatly affected DNA methylation age.


Limitations of the Study

• The study used Arabidopsis as the model.
• The study approach was computational.


How Can We Obtain Nucleic Acids?

• Seeds, grains, fish eggs, muscle tissue, meat, and yeast are good sources of nucleic acids like DNA and nucleotides like ATP.

Genetic Disorders


• Genetic disorders occur when a mutation (a harmful change in a gene or the wrong amount of genetic material) affects your genes.

• Genes are made of DNA containing instructions and characteristics that make you unique.
• Types of genetic disorders:
  • Chromosomal disorders (affecting chromosome structure): Down syndrome, fragile X syndrome, triple X syndrome, and others.

  • Complex disorders (multifactorial): Late onset Alzheimer's disease, arthritis, autism, etc.

  • Single-gene disorders (monogenic): Cystic fibrosis, Duchenne muscular dystrophy, etc.

Klinefelter Syndrome

• A common male condition that results when a person has an extra X sex chromosome (XXY, XXXY, XXXXY).
• Typical characteristics include small firm testicles, small penis size, low sperm count.


Turner Syndrome


• A condition that affects females, resulting from one missing or partially missing X sex chromosome.
• Typical characteristics include short stature, underdeveloped ovaries, and possible heart defects.

Spina Bifida

• A condition where the spine and spinal cord don't form properly during fetal development.

• Three types: occulta, meningomyelocele, and myelomeningocele.
• Occulta is mild and hidden.
• Myelomeningocele and meningomyelocele are more serious.

• May also involve loss of movement in the legs, and bladder and bowel dysfunction.

• Often more common among Hispanic and White populations due to insufficient folate in the pregnant person's body.

Late-onset Alzheimer's Disease


• Common form of dementia.
• Onset is generally at age 65.

• Characterized by memory and cognition issues and impaired judgment, although rare onset may happen as early as 30.

Cystic Fibrosis

• Inherited disorder causing severe damage to lungs, digestive system, and organs.
• Affects cells producing mucus, sweat, and digestive juices;
• The condition leads to thickened mucus in the lungs and other affected organs or systems and causing health problems.

Duchenne Muscular Dystrophy

• A condition causing skeletal and heart muscle weakness that gets worse over time.

• Typically onset is before age six causing progressive muscle weakness and atrophy.
• Common symptoms include toe-walking, calf muscle hypertrophy, fatigue, difficulty climbing up stairs, frequent falls, breathing problems, learning differences, delayed speech, and short stature.

Trends and Issues in the Study of Nucleic Acids


• One trend is the development of a Japanese diet that may slow cancer cell growth.

• A specific example are compounds in Japanese foods (such as nucleic acids from salmon and torula yeast) that impact cell growth and potential cancer prevention.

• Another trend is gene therapy, which is a new treatment being developed for genetic defects and involves human and animal trials to treat issues such as cystic fibrosis.


• CRISPR technology is a tool that is also used in gene therapy that aims to change unhealthy proteins produced due to disease-causing genes.


CRISPR

• CRISPR is an immune system used by microbes to find and eliminate unwanted invaders (e.g., viruses).
• CRISPRs are sequences of DNA that appear in microbes and identify "genetic patterns".

• CRISPR is used to understand an organism’s immune system and help scientists in gene editing, etc.