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7120 Lecture Notes - Lecture 5: Cerebrospinal Fluid, Neural Development, Mendelian Inheritance

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rosesnake902
21 Jun 2018
School
University of Canberra
Department
University of Canberra
Course
7120
Professor
all

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LECTURE 5 – genetics, evolution
Genetics and behaviour
- Both genes and environment interact to shape human behaviour
- Fundamental issue is how much is genetics and how much is due to environment
oIe weight gain, sexual orientation
Mendelian genetics – DNA and RNA
- A gene is defined as a portion of a chromosome and is composed of DNA
- DNA serves as a model for the synthesis of RNA
- RNA is a single strand chemical that can serve as a template/model for the synthesis of
proteins
Mendelian genetics
- They determine development of body by
- Forming part of the structure of the body
- Serving as enzymes. Biological catalysts that regulate chemical reactions in the body
- Being heterozygous for a gene means that a person has an unmatched pair of genes on the
two chromosome
- Being homozygous for agene means that a person has an identical pair of genes on the two
chromosomes
- Genes are dominant or recessive or intermediate
- Recessive needs to be homozygous
Types of genes
- Autosomal genes; genes that aren’t sex linked
- Sex linked genes; located on sex chromosomes
- Sex chromosomes are X and Y
oF – XX
oM – XY
X and Y
- Females give X, men give either Y or X to determine sex of child
Genetic changes
- Mutation: heritable change in dna molecule
- Micro duplication or deletion; appear once, twice or not at all
- Eg schizo; may be a result of micro duplications and deletions of brain relevant genes
Epigenetics
- Concerned with changes in gene expression without modification of DNA sequence
oSome only active in certain parts of life
oChanges in gene expression are central to learning and memory
Heritability
- How much characteristics depend on genetic differences
oFound evidence that heritability in almost every behaviour they have tested
oStrong environmental influences may cause genetic influences to have less of an
effect
How genes affect behaviour
- Don’t directly produce behaviours
- Produce proteins that inc probability of behaviours occurring under certain circumstances
- Have an indirect affect
oCan alter environmental by making traits that alter how people react to you
Evolution of behaviour
- Change in frequency in various genes in a population over generations
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oRegardless of whether the change is helpful or harmful to the species
- Evolution attempts to answer two questions
oHow did some species evolve?
oHow do species evolve?
How do species evolve
- Offspring resemble
- Mutation, recombinationand duplication of genes can introduce new variations
- Survival of fittest
Development of the brain
- Depends on
oMaturation and learning
- Understand this by
oNeurons development
oAxon connection
oExperience modifies development
Maturation of brain
- CNS forms at about 2 weeks in the embryo
Cerebrospinal fluid
- Fluid filled cavity becomes central canal of spinal cord and the four ventricles of the brain
oThis is called cerebrospinal fluid
Development of neurons
- Proliferation
oProduction of new cells in the brain in early life
Early development, the cells lining ventricles divide
Some cells become stem cells to keep dividing
Others stay or migrate
- Migration
oMovement of newly formed neurons and glia to eventual locations
Some don’t reach destinations until adulthood
oOccurs in a variety of directions throughout the brain
Chemicals guide neuron migration
- Differentiation
oForming of the axon and dendrites that gives the neurons its shape
oAxon grows first either during migration or once it has reached target, then
dendrites develop
- Myelination
oGlia produce the fatty sheath that covers the axons of some neurons
Myelin speeds up transmission of neural impulses
First occurs in the spinal cord and then in the hindbrain, midbrain and
forebrain
Occurs gradually for decades
- Synaptogenesis
oFormation of synapses btw neurons
Occurs throughout the life as neuron are constantly forming new
connections and getting rid of old ones
Slows down later in life
Life span of neurons
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- Skin cells are the newest, most under a year old
- Heart cells; old as you are
- Mammalian cerebral cortexes form few or no new neurons after birth
- New olfactory receptors continually replacing dyuing ones
Pathfinding by axons
- Reach target area by following gradient of chemicals in which they are attracted by some
chemicals and repelled by others
- Sperry 1954
Competition with axons
- The form synpases with several cells when target reached
- Strengthen connection, eliminate other connections
oDepends on pattern
Determinants of neuronal survival
- Nerve growth factors – protein that promotes survival and growth
oOverproduces neurons in development then needs to limit i=number
Neurotrophins
- Chemicals to promotes survival and activity of neurons
oAxons not exposed to it – mechanism of cell death
oHealthy adult nervous system - no neurons that failed to make good connections
Differentiation of the cortex
- Neurons in diff parts of the brain differ from one another in shape and chemical components
oImmature neurons transplanted toa developing part of the cortex develop the
properties of the new location
oNeurons transplanted at a later stage of development develop some new properties
but retain some old properties
Fine tuning by experience
- Can reorganise itself in response to experience
oAxons and dendrites continue to modift their structure and connections throughout
life
oDendrites grow new spines
- Gain and loss of spines indicates new connections – learning
Music training
- MRI reveal
oTemporal lobe of pro musicans in RH is 30% larger than non musicians
oThicker gray matter in part of the brain responsible for hand control and vision of
pro keyboard players
oPracticing skill – brain can maximise perf
When brain recognition goes too far
- Focal hand dystonia or musicans cramp refers to when the reorganisation of the brain goes
too far
oFingers of musican who practice extensively become clumsy, fatigue easily and make
involuntary movements
oResult of extensive reorganisation of the sensory thalamus and cortex so that touch
responses to one finger overlap those of another
Brain development and behavioural development
- Teens tend to be more impulsive
oDrinking, sex
- Tend to discount the future
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Document Summary

Both genes and environment interact to shape human behaviour. Fundamental issue is how much is genetics and how much is due to environment: ie weight gain, sexual orientation. A gene is defined as a portion of a chromosome and is composed of dna. Dna serves as a model for the synthesis of rna. Rna is a single strand chemical that can serve as a template/model for the synthesis of proteins. Forming part of the structure of the body. Biological catalysts that regulate chemical reactions in the body. Being heterozygous for a gene means that a person has an unmatched pair of genes on the two chromosome. Being homozygous for agene means that a person has an identical pair of genes on the two chromosomes. Sex chromosomes are x and y: f xx, m xy. Females give x, men give either y or x to determine sex of child. Micro duplication or deletion; appear once, twice or not at all.

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Related Questions

My instructor sent me this in an email to study for a final.Please help me construct the best possible answer for this as Ihave not written a satisfactory answer to the first question allsemester.

1) As you know the final does include a comprehensive componentregarding the gene and genome. (80 pts)

This first question has to be extremely detailed. For example,"A gene is a unit of inheritance. The gene carries information forit to be passed from one generation to the next. When you combine agene with the environment you are five the necessities for aphenotype. There are many gene types and elements such as the genesfor RNAs that carry information to make proteins, genes fortransfer RNAs that carry amino acids to the ribosomes, genes forribosomal RNAs that are required for structure, function andactivities of a ribosome, genes for small nuclear RNAs that make upthe spliceosome and help to splice introns, and the genes fortelomerase RNA component (TERC). A gene must also include manyparts such as introns, exons, core promoters, regulatory promoters,activators, downstream promoter enzymes (DPE), and many others.These parts of the genes as well as the different gene types mustallow for some variation in certain conditions to allow evolutionto occur. A gene must also be able to be passed on, or inheritedfrom one generation to the next." Figures and drawings are alsoappreciated by my instructor. If you could basically just throweverything you can think of within a gene or a genome at thisquestion that would be greatly appreciated.

2) You will also need to study genetic mapping, DNA as a digitalstorage device, X chromosome inactivation and synthetic biology.(35 pts)

DNA Structure and Function LabReport

  1. DNA Structure
  2. Which two scientists are credited with discovering DNA?
  1. Name the nitrogen bases that are purines.
  1. Which nitrogen base pairs with thymine?
  1. List the three components of a nucleotide.
  1. DNA Replication
  2. What is the purpose of DNA replication?
  1. How many times does replication occur in the life of acell?
  1. In the Lab, Exercise 2, the original strand on the left had thebases shown below. Input the new bases that correctly pair with theoriginal strand.

Original

New

C

A

G

T
  1. RNA Structure
  1. Describe the structure and function of RNA.
  1. Refer to Exercise 3 and record the bases of the RNA strandproduced from the replicated DNA strand.

DNA

RNA

C

A

G

T

  1. Record the differences between DNA and RNA in the tablebelow.

DNA

RNA

Sugars

Bases

Strands

  1. RNA Synthesis

  1. The process of assembling RNA is called _________.
  1. How is replication different from transcription?
  1. Refer to Exercise 4. Write the letters for the base sequence ofmRNA in the spaces below DNA. Note that the order is reversed;start with the 3’ end of the DNA strand and the 5’ end of the mRNAstrand. Transcription is DNA to mRNA. Note RNA contains Uracilinstead of Thymine; There is no thymine in RNA.

DNA

3’

C

G

T

C

G

T

C

C

A

A

T

T

5’

mRNA

5’

3’

  1. Protein Synthesis

  1. What type of RNA provides amino acids to build polypeptidechains?

  1. If a mRNA strand has the bases 5’ CUC 3’, what amino acid willbe translated? Refer to the printable chart in Exercise 5.

  1. Where in the cell does translation occur?
  1. Genes

  1. What could be the problem if there is a change in the basesequence of a gene as it is passed down to the offspring?
  1. Give an example of a disorder that results from changes in theamino acid sequence.
  1. What causes sickle cell anemia?
  1. Gene Cloning
  1. What is the function of a plasmid?
  1. Print the document from Lab, Exercise 6. Complete the activityalong with the video demonstration. Sign, date, and take an imageof your final product and include with this lab report.

About 250 companies on the Internet now sell genetic tests directly to consumers. These companies include 23andMe, Navi- genics, GenePlanet, Gene by Gene, DNA Tribes, Genelex, Genova Diagnostics, Sure Genomics, Suracell, African Ances- try.50 The companies ask customers to collect a sample of their genetic DNA with a cheek swab and send it to them for testing. During testing, most companies put the customer’s gene sample on a small flat “DNA microarray chip” that already contains pieces of DNA matching known genes (or gene mutations). If one of the customer’s genes matches one of the pieces of DNA on the chip, it binds to the DNA fragment, which creates a tiny fluorescent glow showing that the gene indicated by the DNA fragment is in the sample. A computer then analyzes the pattern of glowing spots on the chip and prints out a list of the genes (or gene muta- tions) in the customer’s sample. Scientists have discovered a few genes that are associated with specific diseases or personal characteristics. Studies found, for example, genes or gene muta- tions that are linked to cystic fibrosis, Tay Sachs disease, and Lou Gehrig’s disease, genes that increase the risk of certain breast, colon, and thyroid cancers, and genes associated with sensation seeking, eye color, obesity, and lactose intolerance. They also found that some genes are more often found in people whose ancestors came from certain regions of the world. The gene- testing companies say that based on these studies and their own genetic research, they can give customers valuable personalized information (for a price, of course).

Critics say that some companies make claims that have little scientific validity. One company, Gene Planet, advertises on its website that it provides “an individually tailored diet and life-style plan based on a genetic analysis of each individ- ual . . . based on the fact that each individual possesses a
to bear all the costs of injury. Such a distribution of costs would seem to be more fair than imposing the costs on a few victims.
Underlying this third view of the duties of the manu- facturer are the standard utilitarian assumptions about the value of efficiency. This view assumes that an efficient use of resources is so important for society that social costs should be allocated in whatever way will lead to a more efficient use and care of our resources. On this basis, the social costs view argues that a manufacturer should bear the social costs for injuries caused by defects in a product even when no negligence was involved and no contractual relationship existed between the manufacturer and user.
specific genetic makeup and therefore each individual has spe- cific nutritional needs.” Another site promises: “Based upon . . . [genetic] analysis, Suracell recommends to each client a personalized regimen of nutraceuticals [vitamin supple- ments].” Thirty companies offer to identify people’s ancestry based on their genetic profiles. One company, for example, states: “DNA Tribes . . . uses genetic material . . . to measure your genetic connections to individual ethnic groups and major world regions.” Several companies offer paternity testing and “infidelity” tests, including a British company named “Who’z the Daddy?” Thirty-eight companies claim they test for genes related to athletic performance, such as DNA Fit, which adver- tises that “we test your DNA for 20 key genes to help you truly understand your body, and how best to train for your genetics.” For $1,500 Map My Gene offers to test for 46 distinct talents and character traits such as optimism and shyness.
A couple of companies offer to test for compatibility between lovers. Instant Chemistry, Inc., for example, claims on its web- site that “scientific research has shown that relationship markers—a combination of genetics and psychology—strongly affect who we are attracted to and how successful our relation- ships are. . . . Complementary genes result in a higher level of physical attraction and a higher likelihood of a long-term stable relationship.” Some companies, like Chemlaba, claim to do it all: “With a simple saliva sample we’ll help you gain insight into your traits, from baldness to muscle performance. Discover risk fac- tors for 95 diseases. Know your predicted response to drugs, from blood thinners to coffee. And uncover your ancestral ori- gins.” Critics claim, however, that with a few exceptions, most studies have shown only weak connections between genes and specific traits, disease risks, drug responses, nutritional or vita- min needs, talents, athletic performance, compatibility, or ancestral origins. Many studies that link specific genes to a dis- ease are only preliminary, and the full picture has not yet been worked out, while other studies conclude that many traits are the result of complex and unclear interactions among many genes and the environment.

Evaluate the ethics of selling gene tests directly to consumers like these companies are doing. What would each of the three theories of a business's duties to consumers say about what the companies are doing? Under what conditions do you think selling the tests would be ethically legitimate, and why?