Cset 119 Study Notes

Page 1

Genetics ad Evolution

Explain the inheritance of traits which are determined by one or more genes, including dominance, recessiveness, sex linkage, phenotypes, genotypes, and incomplete dominance Traits which are determined by one or more genes and are inherited, in the study of genetics, through the law of segregation where an organism possesses two factors each trait but each sex cell (gamete) only contains one of these factors(alleles) to pass on to the offspring.

Dominance: this the factor(allele) that is dominant to the other

Recessive: this is the factor that is fully masked by other

Sex linkage: Sex-linked inheritance is the inheritance of traits that are located, specifically ,on genes on the sex chromosomes

phenotypes: the physical expression of the traits

genotype: description of the combo of alleles on a single gene

Trait: a genetically determined characteristic.

incomplete dominance: one allele is full dominant over the other

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Asexual Reproduction: a form of reproduction in which a new individual is made by a single parent

*bacteria, insects, and some fish, flatworms, lizards

* share exact genetic info as parents

* this process is faster; does not require another to finish the process

* in this process genetic info cannot be combine from both parents for a more viable offspring

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Sexual Reproduction: gametes from two parents unite to form a genetically unique individual

*two parents are involved

* this process tends to be slower than the latter due to the involvement of mom and dad

* the male produces sperm and the female produces (fertilization) the egg and a zygote is formed and divides into and grows into an embryo

* requires fertilization (external and internal, cross pollination)

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the coding DNA controls the expression of traits via genes by : containing instructions to make amino acids which specifically come together to make proteins -each strand of DNA contains specific sequences (genes) that code for specific proteins ( Genes are expressed by the transcription of DNA into RNA which is then translated to protein -------)

* DNA (in nucleus) sends instructions,mRNA, to ribosome (in cytoplasm)

* tRNA and rRNA are involved in the process of odering amino acids to form protein

* Transcription: mRNA made by DNA template-process of constructing an mRNA molecule from DNA

-double helix unwinds and nucleotides follows same rules for pairing except U is paired A

- each gene contains triplets of bases which are transcribed into RNA and evvery triplet or codon codes for a unique amino acid

* Transcription:

1. mrna travels to nucleus from nucleus

2. base code in mRNA determines order of amino acids in proteins

3. tRNA reads the mRNA code and brings the appropriate AA and each tRNA only carries one AA and only recognizes one specific codon

4. tRNA is released from AA

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A mutation is a permanent change in the sequence of DNA

*point mutations: small changes(a change in a single nucleotide-base) in the DNA sequence : this causes frameshifts

*chromosomal mutations:

-Deletion: loss of a DNA segment -missing segment in the chromosome

-Duplication: seg of DNA is repeated making a longer chromosome

-Inversion: seg of DNA is flipped then reattached to the chromosome

-Insertion: seg of DNA from one chromsome is added another -unrelated chromosome

-Translocation: when two segments from different chromosomes change positions

* Mutations may also be caused by mutagens : like chemicals tobacco smoke

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DNA Replication: DNA is copied to form identical model

* DNA Helix unwinds like zipper as bonds are broken

* two single strands now stand alone as individuals to copied with the right base pairs connected

*new set of necleotides join together to form new strand of DNA resulting in 2 DNA molecules each with one old strand and a new one (semi-conservative replication)

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Describe evidence, past and present, that supports the theory of evolution, including diagramming relationships that demonstrate shared characteristics of fossil and living organisms