chapter 9 - patterns of inheritance

Chapter 9 - Patterns of Inheritance

AIM: Are we born this way or does the environment make us who we are?

TOPIC 3Genetic Continuity



Our next adventure is into genetics or the study of heredity.

Heredity is the passage of design information (DNA) from the parent(s) to the offspring.



Nature vs.

NurtureNature-Nurture is the classic debate concerning genetics (ones inherited genes - nature) vs. environment (nurture). Which is more important? Are you more intelligent than your friend because of the genes you were given by your parents or because of how your parents/teachers/etc… raised you? Or both…



Nature vs.

NurtureWhich do you think is more important, the genes that store the information to build your RNA and proteins, which built your mind, OR the environment that your mind was built in?Where would you look to determine if nature or nurture is more important?Identical twins (better yet, identical twins that were separated at

birth)



The Pit-bull (left) and the Rottweiler (right) were both artificially selected for their aggression and natural tendency to guard objects. This means that this tendency is built into the wiring of their brains, which were built by proteins in cells, which were built from the information stored in the genes, which came from the dog’s parents…



The Pit-bull (left) and the Rottweiler (right) were both artificially selected for their aggression and natural tendency to guard objects. Artificial Selection:When humans choose which offspring to mate,

forcing certain characteristics (traits).

Conclusion:The environment can affect gene expression (how much protein is made, etc…)


AIM: Describe the rules that govern how traits are inherited.

Chapter 3 - The Molecules of Cells

Reminder

AIM: Describe the structure of DNA and RNA?

Chromosomes (DNA; the books) contain thousands of genes (sentences) that code for RNA and in turn protein. **Proteins built you and maintain you and therefore they determine your traits.

Genes therefore determine your traits (the color of your eyes, height, shape of your face, skin color, etc…)Heredity is the passing of ones genes to their offspring.

Chapter 8 - The cellular bases of reproduction and inheritanceAIM: Describe the eukaryotic cell cycle.

Let’s look at the structure of DNA once more quickly

C-GG-CA-TG-CG-CT-AT-AT-AA-TA-TA-TC-GC-GT-AC-GG-C


DNADouble-stranded nucleic acid (the books) stuck in the nucleus (the library) in eukaryotes that contains the information (genes) to build every mRNA, tRNA and rRNA.Chromosome

ChromatinAll of the chromosomes in the nucleus combined.

A single piece of double-stranded DNA and associated proteins like histones. Humans have 46 chromosomes in every cell with a nucleus (a single book).

Immediately after determining the structure of DNA (1953), Watson and Crick proposed what is known as the semi-conservative model of DNA replication, and they happened to be correct although they would now know this until experiments done by American geneticists Meselson and Stahl in 1958…

Chapter 10 - Molecular Biology of the Gene

NEW AIM: How is DNA replicated

DNA REPLICATION


AIM: How is DNA replicated – The semi-conservative model

What must happen first?The DNA strands must separate (hydrogen bonds are broken between A-T and C-G base pairs). An enzyme known as DNA helicase does this (an enzyme that unwinds and opens a helix is called a helicase – get it?)…

GENERAL OVERVIEW

AIM: How is DNA replicated?Chapter 10 - Molecular Biology of the Gene


Now what must happen?

-The two strands called template or parent strands will be used as a template to fill in the new strands.

-The template is what you look at to make a new copy. It is a pattern you follow.

GENERAL OVERVIEW

AIM: How is DNA replicated?

Fig. 10.4A



Nucleotides, which are in high concentration and randomly diffusing around the cell (in the nucleus of eukaryotes, are correctly paired and attached to each other (dehydration synthesis) by the enzyme…

DNA polymerase

GENERAL OVERVIEW

AIM: How is DNA replicated?

Fig. 10.4A



The result is two identical daughter chromosomes, each containing one strand from the original parent molecule and one newly synthesized strand called the daughter strand, which is complementary to the parent strand (semi-conservative).

GENERAL OVERVIEWParent or template strands

Daughter or complementary strands


NEW AIM: How is genetic information transmitted from DNA to protein?

GENE EXPRESSIONGoing from Gene to Protein

Fig. 10.6A

?



How is the genetic information transmitted from DNA to protein so that the proteins can build and maintain you?

Fig. 10.6A

?


AIM: How is genetic information transmitted from DNA to protein?

What is the first step and what enzyme is involved?

Transcribe means to make a written copy. mRNA is a copy of a segment of DNA, a gene. They are the same language – nucleic acid language.

The Central Dogma of Molecular Biology



…and the second step?

By RNA polymerase

Translate means to convert between languages. In this case, nucleic acid language is translated into amino acid language by the ribosome and tRNA.




By the ribosome and tRNAs

Reminder (analogy):


Do bacteria have a library?They do not have a nucleus…transcription occurs in the semifluid (cytoplasm)



The nucleus is the library, the DNA/chromosomes are the reference books that cannot leave the library, and the mRNA is the transcription or copy of a small part of the DNA, a gene, that is slipped through the nuclear pore to a ribosome (rRNA + proteins) in the cytosol that will be involved in translating the nucleic acid language into amino acid language (a polypeptide) with the help of tRNA.

Fig. 10.7



Reminder:A single chromosome has thousands of genes…

Each gene codes for?

A complementary piece of RNA (mRNA, tRNA or rRNA)If the gene codes for mRNA, then the mRNA

will code for?A protein



(Translating DNA/RNA Language into amino acid language)

Cracking the Genetic Code

Genetic Code:The rules by which information is encoded in DNA/mRNA and translated into polypeptide sequences.

RNA =

What does the “sentence” say?

The chromosomes are books, which would make a gene just one sentence in these books…Chromosomes = Books

Gene = Sentence in the BookA copy of the sentence




All English books are written using 26 letters arranged into different combinations to make words, which are combined to make sentences... RNA Nucleic Acid Language is MUCH simpler…





RNA Nucleic Acid Language is MUCH simpler…

1. There are only 4 letters (A,U,G,C)


2. These letters combine to make “words”, called codons, which are only 3 letters long.




How many different codons can be made from the four letters?

RNA Nucleic Acid Language is MUCH simpler…

1. There are only 4 letters (A,U,G,C)

4 x 4 x4 = 64*Only 64 words in the entire language!!(It could not be any simpler and still work)


2. These letters combine to make “words”, called codons, which are only 3 letters long.



(Deciphering DNA/RNA Language)

Cracking the Genetic CodeWhat do these 64 codons code for?

1. Sixty-One of the codons code for an amino acid






Example: The codon AUG codes for the amino acid Methionine (Met) – this is typically the first or starting codon, which make __________ the first amino acid of most proteins

Methionine






Example: The codon AUG codes for the amino acid Methionine (Met) – this is typically the first or starting codon, which make __________ the first amino acid of most proteins 2. Three of the codons tell the ribosome to stop – UAG, UAA, UGA

Methionine

NEW AIM: How is genetic information transmitted from DNA to Protein?

The Genetic CodeFig. 10.8A

The genetic code was cracked in the 1960’s,

just after the structure of DNA was elucidated.

The chart to the right is used to look up any RNA codon and determine the amino acid it codes for…

NEW AIM: How is genetic information transmitted from DNA to Protein?

The Genetic CodeFig. 10.8A

There are Sixty-One codons coding for amino acids, but there are only how many amino acids?

20

What does that mean?Some amino acids are coded for by more than one codon like Leu, which is coded for by 6 codons!

AIM: How is genetic information transmitted from DNA to Protein?

Fig. 10.15

OVERVIEW

This is it! This is how every RNA/polypeptide in all of your cells is made starting from the gene!!

Mutagenesis


NEW AIM: How are genes altered and what is the result?

Therefore, mutagenesis means to “Produce a mutation” or to produce any change in the DNA sequence of an organism.

Muta- = mutation = any change in the sequence of DNA-genesis = origin or production of

What causes mutations?


AIM: How are genes altered and what is the result?

1. Radiation



- UV light from the sun- gamma rays from outside Earth (ex. Distant supernova)- Soil and certain rocks in the Earth’s crust contain radioactive radon gas

mutations

-color TV, smoke detectors, computer monitors, X-ray machines, nuclear plants, etc…

1. High energy radiation



A. Mutagens (carcinogens)Induced mutations



B. Pollutants 2. Chemicals

Ex. Cigarette Smoke




AcetaldehydeAcetamideAcrylamideAcrylonitrile2-Amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQ)3-Amino-1,4-dimethyl-5H-pyrido [4,3-b]indole (Trp-P-1)2-Amino-l-methyl-6-phenyl-1H-imidazo [4,5-b]pyridine (PhlP)2-Amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1)3-Amino-l-methyl-5H-pyrido {4,3-b]indole (Trp-P-22-Amino-3-methyl-9H-pyrido[2,3-b]indole (MeAaC)2-Amino-9H-pyrido[2,3-b]indole (AaC)4-Aminobiphenyl2-Aminodipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2)0-AnisidineArsenicBenz[a]anthraceneBenzeneBenzo[a]pyreneBenzo[b]fluorantheneBenzo[j]fluorantheneBenzo[k]fluorantheneBenzo[b]furanBeryllium1,3-Butadiene

CadmiumCatechol (1,2-benzenediol)p-ChloroanilineChloroformCobaltp,p'-DDTDibenz[a,h]acridineDibenz[a,j]acridineDibenz(a,h)anthracene7H-Dibenzo[c,g]carbazoleDibenzo(a,e)pyreneDibenzo(a,i)pyreneDibenzo(a,h)pyreneDibenzo(a,i)pyreneDibenzo(a,l)pyrene3,4-Dihydroxycinnamic acid (caffeic acid)EthylbenzeneEthylene oxideFormaldehydeFuranGlycidolHeptachlorHydrazineIndeno[1,2,3-cd]pyrene

IQ 92-Amino-3-methyl-3H-imidazo[4,5-f]quinoline)IsopreneLead5-Methyl-chrysene2-NaphthylamineNitrobenzeneNitrogen mustardNitromethane2-NitropropaneN-Nitrosodi-n-butylamine (NDBA)N-Nitrosodi-n-propylamine (NDPA)N-Nitrosodiethanolamine (NDELA)N-Nitrosodiethylamine (DEN)N-Nitrosodimethylamine (DMN)N-Nitrosoethylmethylamine (NEMA, MEN)4-(N-Nitrosomethylamino)-1-(3-pyridinyl)-1-butanone (NNK)N'-Nitrosonornicotine (NNN)N-Nitrosopiperidine (NPIP, NPP)N-Nitrosopyrrolidine (NPYR, NPY)Polonium-210 (Radon 222)Propylene oxideSafroleStyreneTetrachloroethyleneo-Toluidine (2-methylaniline)

TrichloroethyleneUrethane (carbamic acid, ethyl ester)Vinyl acetateVinyl chloride4-Vinylcyclohexene2,6-Xylidine (2,6-dimethylaniline)

A List of known carcinogens in cigarette smoke



i. Acesulfame K

ii. Artificial coloring (blue-1, blue-2, red-3, yellow-6)iii. BHA and BHTiv. Nitrite and Nitratev. Olestravi. Potassium Bromate

D. Food Additives

2. Chemicals




5. Certain drugs

6. Viruses (Oncoviruses)

a. HPV (Human Papilloma Virus)b. EBV (Epstein Barr Virus)c. Hepatitis C virus

Ex. Chemotherapy drugs


Types of Mutations that can occur.



Fig. 10.16B



Types of Mutations

1. Point mutations – this type of mutation is called a point mutation because it happens at a single point (single letter)



Types of Mutations



Types of Mutations

In this case, the mutation caused an amino acid change in the protein, which will cause a structural change in the protein/polypeptide and possibly a change in the protein’s function.

Fig. 10.16B



Types of Mutations

2. Deletions – one or more nucleotides are lost.

If a multiple of 3 are lost (3,6,9,etc…), then only those amino acids are lost from the polypeptide. However, if any other number are lost, all the amino acids change (called a reading frame shift or a frame shift mutation).



Types of Mutations

3. Insertions – one or more nucleotides are gained. If a multiple of 3 are inserted (3,6,9,etc…), then new amino acids are added to the polypeptide. However, if any other number are inserted, all the amino acids change (reading frame shift).

Cause of Tay Sach’s



Types of Mutations

4. Inversions – Segments of the DNA get flipped (inverted)



Types of Mutations1. Point mutants or substitutions

2. Deletion3. Insertion4. Inversion

Somatic

Germline mutationsvs



Somatic (body cell) mutations



Mutations occurring in body cells that can lead to cancer, but are not heritable (CANNOT be passed to offspring).Cancer is NOT heritable, but the predisposition to get cancer IS!

Is cancer itself heritable?

Germline mutations



Germline cells

Mutations that occur in these cells can be inherited by the offspring. These are the critical ones in terms of evolution.

How are these mutations different?

- gametes and the cells that will become gametes after meiosis.

What do all these germline mutations have in common whether positive or negative?



The mutations Randomly Create New Genes

Without mutation, there would be no new genes, organisms would never change (no evolution!). Why would this not be good?Because the environment changes over time, and

if organisms cannot change to keep up with it there will be no organisms.

Chapter 12 - DNA Technology and the Human Genome

Genetically modify organisms and transgenic organisms

GENETIC ENGINEERING



Genetically modified organisms (GMO’s):

-Organisms whose genes have been altered using genetic engineering techniques.

- Most GMO’s are transgenic organisms… they have received genes from a different organism.

Transgenic organisms

Ex. A mouse is given a gene from a human. The mouse is a transgenic GMO.

Trans- ; across (across species in this case)


Genetically modify organisms (GMO’s) and transgenic organisms

GloFish1. Zebra danio was genetically engineered with a gene from sea coral that causes the fish to glow in the presence of environmental toxins.2. Gene was inserted into the embryo of the fish.

Zebra danio

3. First GMO available as a pet.

GMO’s at home:


Genetically modify organisms (GMO’s) and transgenic organisms

Ordinary rice“Golden” rice

- “Golden” rice is genetically engineered with genes that code for enzymes that make beta-carotene, a precursor to Vitamin A for countries deficient in foods with Vit. A…

- This rice has never been used because of environmental concerns.

GMO food:



Genetically engineered sheep with the human gene for alpha-1-antitrypsin (AAT). AAT is extracted from their milk and used to treat humans deficient in AAT, which is one cause of emphysema (a breathing disorder) in approximately 100,000 people in the western world.

AAT Sheep

GMO medicine:



- Insulin is made using the bacterium E. coli.

- The human gene coding for insulin is inserted into E. coli, which will then make insulin for us (we will see how this is done shortly)…

E. Coli with the human insulin gene

GMO medicine:

Fig. 12.3


How can we use bacteria to manipulate DNA and protein?

Review Slide

Bacterial and human DNA is cut using restriction enzymes (enzymes that act like DNA scissors)

The DNA is then combined and added back to a bacterium, which will make the protein or more of the gene when it divides.

chapter 9 - patterns of inheritance

Documents

patterns of inheritanceaim

environment nurture

thousands of genes

birth chapter

passing of ones genes

eukaryotic cell cycle

cellular bases of reproduction

structure of dna