Genome Sequencing and Neuron Theory Quiz

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Questions and Answers

What is the primary function of sensory neurons?

Associate sensory and motor activities

Transmit signals from the brain to the body

Conduct information from sensory receptors to the CNS (correct)

Carry information to the body's muscles

Which type of neuron is responsible for linking sensory and motor neurons?

Motor neurons

Stellate cells

Interneurons (correct)

Pyramidal cells

What characterizes pyramidal cells?

They possess a pyramid-shaped cell body with two sets of dendrites. (correct)

They have simple structures with minimal branching.

They are small with many dendrites extending around the cell body.

They have a single long axon and numerous short dendrites.

Which type of neuron is known for having two types of dendrites, apical and basal?

Pyramidal cells Signup and view all the answers

What is one important feature of Purkinje cells?

They have extremely branched dendrites forming a fan shape. Signup and view all the answers

Which type of neuron connects sensory information from the retina to the visual centers of the brain?

Bipolar neurons Signup and view all the answers

What is the relationship between the number of interneurons and brain size?

Larger brains contain significantly more interneurons than smaller brains. Signup and view all the answers

What is a key characteristic of motor neurons?

They have extensive dendritic networks. Signup and view all the answers

What is the primary function of microglia in the brain?

Engulfing foreign tissue and dead brain cells Signup and view all the answers

Which type of glial cells myelinate axons in the peripheral nervous system?

Schwann cells Signup and view all the answers

How does myelin affect neuronal communication?

It enables faster signal transmission Signup and view all the answers

What is a characteristic of Multiple Sclerosis (MS)?

It is associated with damage to oligodendroglia Signup and view all the answers

What negative effect can microglia have in response to inflammation?

They consume inflamed tissue Signup and view all the answers

What happens to neurons when oligodendroglia and Schwann cells are damaged?

There is a severe impact on function Signup and view all the answers

In what scenario may recovery occur in the event of axon severance?

Recovery may take weeks to months Signup and view all the answers

What is one potential function of microglia regarding nearby brain regions?

They identify damaged cells in the brain Signup and view all the answers

What condition did the Beery twins initially develop that was later diagnosed as dopa-responsive dystonia?

Cerebral palsy Signup and view all the answers

Which treatment led to significant improvements in the Beery twins' condition?

L-dopa Signup and view all the answers

What genetic finding was discovered during the sequencing of the Beery twins’ genomes?

Abnormality in a gene affecting dopamine and serotonin production Signup and view all the answers

What is the significance of Alexis competing in junior high school track after treatment?

It indicates the successful impact of precision medicine. Signup and view all the answers

What was the primary conclusion made by Santiago Ramón y Cajal about the nervous system?

Neurons are the functional units of the nervous system. Signup and view all the answers

What technique did Camillo Golgi develop to visualize nervous tissue?

Silver nitrate staining Signup and view all the answers

What aspect of precision medicine is highlighted by the Beery twins' case?

The application of individualized genetic therapies Signup and view all the answers

What was the unique outcome of genome sequencing in the Beery twins’ treatment?

It led to remarkable improvements in motor abilities. Signup and view all the answers

What is the primary role of the phospholipid bilayer in cells?

To act as a barrier to many substances. Signup and view all the answers

Which part of the phospholipid molecule is hydrophilic?

The phosphorus head. Signup and view all the answers

How many chromosomes do human somatic cells typically contain?

46 chromosomes. Signup and view all the answers

What is the function of RNA during the transcription process?

To serve as a blueprint for protein synthesis. Signup and view all the answers

Which nucleotide base replaces thymine in RNA?

Uracil. Signup and view all the answers

What is the average number of base pairs in a human gene?

30,000. Signup and view all the answers

What occurs during the process of transcription?

The gene unwinds to expose its bases. Signup and view all the answers

What is the main purpose of the nucleus in a cell?

To store and send genetic information. Signup and view all the answers

What are the chromosomes numbered 1 to 22 called?

Autosomes Signup and view all the answers

What is the role of the SRY gene found on the Y chromosome?

Triggers male phenotype development Signup and view all the answers

Which of the following describes homozygous alleles?

They are identical alleles. Signup and view all the answers

What does complete dominance mean in terms of allelic expression?

Only the dominant allele's trait is expressed. Signup and view all the answers

What is a single nucleotide polymorphism (SNP)?

A change in a single nucleotide base. Signup and view all the answers

Which type of dominance allows both alleles' traits to be expressed completely?

Codominance Signup and view all the answers

What type of alleles can be passed onto future generations even if not expressed in the phenotype?

Recessive alleles Signup and view all the answers

How can genetic mutations affect proteins?

They can change codons and alter amino acids. Signup and view all the answers

Study Notes

Fraternal Twins and Genome Sequencing

Fraternal twins Alexis and Noah Beery were diagnosed with cerebral palsy but their condition worsened over time.
Their mother, Retta Beery, suspected dopa-responsive dystonia after watching a news report.
Daily l-dopa treatment, converted into dopamine, significantly improved their condition.
Alexis developed breathing difficulties leading to further genetic analysis.
Genome sequencing revealed an abnormality in a gene affecting dopamine and serotonin production.
Adding 5-hydroxytryptophan, a serotonin precursor, to the treatment further improved their motor abilities.
This is the first case where genome sequencing led to successful treatment, promoting precision medicine.

Neuron Theory

The neuron theory, proposed by Santiago Ramón y Cajal, states that neurons are the functional units of the nervous system.
More neurons lead to more complex behavior.
This theory emerged from a debate with Camillo Golgi, who believed the nervous system was an interconnected network of fibers.
Both Golgi and Cajal received the Nobel Prize in 1906 for their work on nervous system cells.

Types of Neurons

Sensory neurons transmit information from sensory receptors to the spinal cord and brain.
Interneurons associate sensory and motor activity within the central nervous system (CNS).
Motor neurons carry information from the brain and spinal cord to muscles.

Sensory Neurons

Bipolar neurons are found in the retina of the eye, transmitting sensory information from light receptors to the brain.
Somatosensory neurons bring sensory information from the body to the spinal cord over long distances.

Interneurons

Interneurons, also called association cells, link sensory and motor neurons.
Stellate cells, a type of interneuron, have many dendrites and a hard-to-see axon.
Larger brains have more interneurons due to their increased behavioral complexity.
Pyramidal cells have a long axon and a pyramid-shaped cell body with two sets of dendrites.
Purkinje cells have highly branched dendrites and carry information from the cerebellum to the rest of the brain.

Motor Neurons

Motor neurons have extensive dendritic networks to collect information from multiple sources.

Glial Cells

Glial cells support neurons in various ways.
Astrocytes are star-shaped cells that help with nutrition, waste removal, and the blood-brain barrier.
Microglia are the immune cells of the brain, engulfing foreign tissue and dead brain cells.
Oligodendroglia myelinate axons in the brain and spinal cord, while Schwann cells myelinate axons in the peripheral nervous system.

Myelin

Myelin acts like insulation on electrical wires, preventing neurons from short-circuiting and facilitating faster information transmission.
Neurons that send messages quickly over long distances are heavily myelinated.
Both Schwann cells and oligodendroglia also help in neuron nutrition and functioning.

Glial Cells and Disease

Damage to oligodendroglia and Schwann cells can severely impact nervous system function, similar to neuron damage.
Multiple sclerosis (MS) is a degenerative nervous system disorder often related to damage to oligodendroglia, resulting in scar tissue and impaired information flow.
Glial cells assist in nervous system repair after axon severance.

Cell Membrane Structure

The cell membrane is composed of a phospholipid bilayer, a selective barrier to many substances.
Phospholipids have hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails.
The bilayer forms with the heads outwards towards water and the tails pointing inwards.
Small nonpolar molecules can pass through, while polar water molecules and charged ions cannot.

Nucleus and Protein Synthesis

The nucleus stores, copies, and sends blueprints for protein and RNA synthesis.
Genes, segments of DNA, encode these blueprints.
Chromosomes are double-helix structures containing an organism's DNA library.
A human somatic cell has 46 chromosomes, while reproductive cells have 23.
DNA consists of two strands with sequences of four nucleotide bases: adenine (A), thymine (T), guanine (G), and cytosine (C).
Base pairing: A pairs with T, and G pairs with C.

Transcription Process

The gene unwinds, exposing bases for protein synthesis.
Free-floating nucleotides form a complementary RNA strand.
The RNA strand detaches and leaves the nucleus, carrying the code for protein synthesis.

RNA Transcription

RNA has a single strand of bases, with uracil (U) replacing thymine (T)
The transcribed RNA strand is called messenger RNA (mRNA), carrying the protein code to the endoplasmic reticulum (ER).

Chromosome Structure

One chromosome from each pair is inherited from the mother and the other from the father.
Pairs are numbered 1 to 23 based on size.
Chromosome pairs 1 to 22 are called autosomes, influencing physical appearance and behavior.
The 23rd pair consists of sex chromosomes (X and Y), influencing sexual characteristics.
The Y chromosome carries the SRY gene, triggering male phenotype development.

Gene Copies and Alleles

Each cell has two copies of every gene (alleles) from both parents.
Homozygous alleles are identical, and heterozygous alleles are different.
The most common nucleotide sequence is the wild-type allele.
Less frequent sequences are mutations, which can be beneficial, neutral, or harmful.

Allelic Expression

Homozygous alleles encode the same protein.
Heterozygous alleles can encode different proteins.
There are three possible outcomes for heterozygous alleles: only maternal, only paternal, or simultaneous expression of both.

Dominance

A dominant allele is expressed as a trait.
A recessive allele is not expressed when paired with a dominant allele.
Complete dominance: Only the dominant allele's trait is expressed.
Incomplete dominance: The dominant allele's trait is partially expressed.
Codominance: Both alleles' traits are expressed completely.

Genetic Mutations

Errors occur in nucleotide sequences during gene reproduction, leading to mutations.
A single nucleotide polymorphism (SNP) is a change in a single nucleotide base, potentially altering protein function.

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Description

This quiz explores the groundbreaking case of fraternal twins Alexis and Noah Beery, whose cerebral palsy was successfully treated through genome sequencing and tailored medication. It also touches on the neuron theory by Santiago Ramón y Cajal, emphasizing the relationship between neurons and behavior. Test your understanding of precision medicine and fundamental neuroscience concepts.