Bio Test Mutations

8/7/2019 Bio Test Mutations

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Bio Test

Mutations


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Types of Mutations

Changes in genetic structure

Phenotype- physical appearance

Genotype- genetic combination

Types: Pointsimplest type of mutation, one BP doesnt line up

Frameshift nonsense- stop codon in the coden halts protein synthesis Silent substitutionthe amino acid is still the same

Missense substitutionchanges the amino acid, changes the phenotype

Deletion/Insertion BP are removed or inserted

Wild type forward mutation- change from wild type

-Backward mutation- back towards wild type

Frameshift will effect phenotype

Block deletion- delete multiple base pairs Translocation mutations part of a chromosome physically moves

Duplication mutationmutiple copies of the same structure (selective environmentalpressures)

(DNA polymerase)


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Cancer

Failure of apoptosis in cells

Failure of contact inhibition signals

Caused by mutations

Metastasis- spreading of cancer cell Oncogene- causes cancerous mutations

Proto-oncogene- gene that is susceptible tomutation that will give rise to uncontrolled

growth (cancer) Testing DNA must be sequenced and compared

to know if presence of proto-oncogene


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Virus

RNA tumor virusretroviral

DNA tumor virus>>>>**?

I. Altered Gene1. Incorporation of retroviral Oncogene

2. Mutation of normal proto-oncogene to create an oncogeneII. Altered gene expression in which a gene is transcribed at the wrong

time, or too high a rate

1. Insertion next to proto-oncogene of retroviral DNA containing anactive control region

2. Translocation of a proto-oncogene to a position next to an activecontrol region3. Translocation of an active control region to a position next toproto-oncogene


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Gene Transfer

Movement of gene from one bacterium to

another can happen in various ways

Mechanical Methods: Transduction Non-mechanical Methods: Transformation,

conjugation


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Transduction-

transfers DNA between bacteria

1. Phage injects its DNA (bacteriophage=

complex bacteria)

2. Phage enzymes degrade host DNA3. Cell synthesizes new phages that incorporate

phage DNA (and mistakenly some host DNA)

4. Transducing phage interjects donor DNA5. Donor DNA is incorporated into recipients

chromosomes by recombination


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Transformation

Most bacteria have the ability to absorb DNA

Can allow a new biochemical organization

Griffiths experiment with the mice


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Conjugation

F+ plasmid=extranuclear DNA

Conjugation pilus= connection between bacterium cells

Graham negative organism- one type of cell wall in

bacteria1. Donor cell attaches to recipient cell with its pilus. Thepilus draws the cells together

2. The cells contact each other

3. The plasmid replicates one of its strands and transfers

the daughter strand to recipient through pilus4. The recipient simultaneously synthesizes a

complementary strand to become an F+ cell


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Plasmid Function

Fertility

Resistance Factor- resist antibiotics

Bacterium Factor- resist chemical treatment

Virulence Factor- increases pathoginicity Cryptic- high frequency Hfr Conjugation, plasmid

splices itself into the host genome, transfers parts ofgenome between cells

Transposable Element (aka transposon or jumping

gene)- small pieces of DNA jump from one chromsometo another- effects phenotypebarabraMaclintock-discovered this with corn


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Chromosome

Centromere-divides chromosome into arms located in thecenter

Metra-centromere- uneven divide Q arms above centromere

Teleocentric- at the end of a chromosome P arms belowcentromere

(chromsone 21,22 have short/non-existent q arms)

Kinetochore- spindle fiber attachment

Acrocentric- v. off center

Telomere- responsible for aging?

Dark band-hetero-chromatin-has high cone adenine + thymine

Light band- euchromatin- high cone of guanine + cytosine

Topological structure- banding patterns, arms length, centromerelocation all help define karyoypes- physical representation of thechromsomes to determine any problems


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Nuclear Division

M- phase mitotic (after build up of M cyclin that builds up in G2 phase)

Entering M phase: 1. the centrioles duplicate, (centrioles are made of tublin- microtubulies ( + ) arrangement)

Mitotic organizing center (MOC) organizes spindle fibers

Prophase:

2. Centrioles move to poles of cell

3. Form short spindle fibers called Aster Rays

4. Forms long spindle fibers5. As fibers move to poles of cell, nuclear envelope and nucleolus disappear

Metaphase:

6. Spindle fibers attach the Kinetochore to outside of centrioles

7. Fibers line up in middle of cell (equator)

8. Centromere duplicates so sister chromatids separate

Anaphase:

9. Spindle fibers start to contract- pulling the chromosome to the centrioles (the poles)

10. Fibers push the cytoplasm in different directions

11. Aster rays pull and push cytoplasm

12. Furrowing takes place cytokinesis

Telophase:

13. As chromsomes approach centrioles- chromsomes relax, spindle fibers diappear


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Cell Plate Formation

Directed by Golgi Apparatus

Phragmoplast (microtubules)- directs the placement of the vesicles

As the materials in the vesicles are released, the vesicles fuse into asolid plate of cellulose to form the cell walls

Right after cell walls are separated- cells must go through anothergrowth period

Acid Growth Hypothesis- cell grows to full size after separating

Cytoplasm of cell pumps H+ in between cell membrane and cell wall

1. Excess of H+ loosens cellulose fibers

2. space in between membrane and wall is hypertonic (water goesin between space and stretches the cell- neutralizes the H+ acid


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Meiosis

Process of gamete production

Nuclear division- reduction division

the total chromosomes in offspring cells

2 nuclear divisions= 4 cells

Om metaphase I instead of line up there is a formation of tetrad

Meiosis is only in gamete cells

(v. similar to mitosis)Only differences:

Homologous chromosomes form tetrad- called chiasmata

When tetrad reaches the equator spindle fiber attaches to the the kineticore of the outside of thetetrad

Separation of the pairs of chromosomes- no centromere duplication

Cells from 2 offspring cells with attached sister chromotids

Interkinesis phase- between divisions

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2nd set of divisions-identical to mitosis!

Result? Offspring cells (4) each have the genetic material of the parental cells

(haploid cells)


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Crossover arms of homo-chromosomes-

exchange tips- create genetic diversity

Synapse-location of crossing over Homologous pairs are connected in middle by

axial protein to form tetra


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Gamete Production (Animals)

Spermatogenesis (males)- at end of meiotic

division end with 4 fertilizing cells (interstitial

cells)

- outcomes are identical in plants and animals

Primary spermatocyte- end up with 4

spermatozoa


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Oogenesis

MetoticDivison I

(If fertalized)

MetoticDivison IIOotid + 3 polar bodies

Ovum-------------------


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Haploid- 1 set of chromosomes

Diploid- 2 sets

Karyogamy- union of nuclei when fertlized=zygote

Thallus- disintegrates after sporyte is

produced (must swim to females)


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Plants

In the 2 major plant groups: conifers & flowering plants

The process of reproduction involves 2 special types ofgamete producing cells Microspore mother cells- divides 2x by meiosis-forms 4 pollen

grams Megaspore mother cells- divides 2x by meiosis to form 4

embryos but 3 dissolve, the lone nucleus then divides by mitosis3x to five a total of 8 nuclei migrate to form the synergids,polar nucli, and anti-podals

Endosperm- food for growing embryo (lipids)- glycolyticpathway using glyoxisomes (made from polar bodies +sperm)

Gymnosperms-growth of tube takes 1 yr so not fertilized till2nd year


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Chromosome Mutations

Involve nondisjunction- failure of homologouschromatids to separate in meiosis

1. 18th chromosome: Edwards syndrome- Full term

infant doesnt live past 1st

month.organ problems, elongated head, often bornw/only brainstem

2. Downs syndrome: called Mongolism. Extra

21

st

chromsome3. Crydocnat- baby sounds like meowing cat. On13th mutation trisome. Hole in heart, organfailure, live


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Reproductive Nondisjunctions

XXY-Klinfelters syndrome: doesnt go throughpuberty- infertile

X-Turners syndrome: 1 of 8000 females born,

short, webbed neck, widely separated nipples,shield shaped chest, learning disorders, sterile

XYY- Jacobs syndrome: 1 in 400 males, tall,aggressive, learning disabilities, tend to be

incarcerated

XXX- metafemale: possibility of learningdisabilities


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Multiple chromosomes

Allopolyploidy- multiple chromosomes due tobreeding

Winter wheat- triploid, grass carp (CAN

reproduce), bananas

Autopolyploidy- m.c. due to to mutation

Direct result of nondisjunction in gametes givingorganisms a natural selection and vantangle-adaption advantage (rare) has to be even-ploid toreproduce


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Genetics

P-generationparental

Pure breeding- homozygous recessive ordominate- aa or AA

heterozygous- Aa or aA

F1 generation- first filial

F2- Second filial

Law of segregating traits (mendel) allelesseparate from each other in division go toseparate gametes Ponnett squares

Bio Test Mutations

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