Molecular Genetics Flashcards by Kelsey Con

What are the complementary base pairs in nitrogenous bases

AT double bond

CG triple bond

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Nucleoside vs nucleotide

Side = base + ribose sugar
Tide = base + sugar + phosphate ( t = t)

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Explain the semi conservative process of DNA replication

Helicase unzips Parent DNA
RNA polymerase creates an RNA primer.
DNA polymerase 3 adds complementary nucleotides on the 3’ end (5’-3’)
RNAse H removes primers
Gaps are filled by DNA polymerase 1 and any nicks are sealed by ligase

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Explain the difference between leading and lagging strand and why that’s a thing

Nucleotides can only be added from 5’ - 3’
Leading is continuously synthesized only requiring one primer
Lagging stars and has Okazaki fragments that require many primers

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Difference between prokaryote and eukaryote DNA replication

Pro - 1 origin of replication on each circular chromosome (plasmid)
Euk - multiple origins on each linear chromsome

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All nucleotide processed go in which direction

5’ to 3’

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What does telomerase do

Lengthen the end of eukaryotic chromosome with telomeres

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Define gene vs genome

Series of DNA nucleotides that code for an RNA product

Genome contains the entire DNA sequence of an organism

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what is the central dogma *****

DNA is transcribed into RNA which is translated into amino acids (proteins)

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4 differences of RNA to DNA

can leave the nucleus (DNA only in nucleus and mitochondria
Uracil instead of thymine
Has an OH group
Single stranded

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Primary rna

Immature strand of mRNA

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Messenger rna

Primary rna is processed to encode for a blueprint used in translation

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Ribosomal rna

Rna component of a ribosome

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Transfer rna

Transfer amino acids to growing polypeptide

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3 phases of transcription

Initiation , elongation, termination

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Initiation phase of transcription

RNA polymerase binds to promoter or TATA box then unzips DNA and forms a transcription bubble

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Elongation phase of transcription

RNA polymerase transcribes the template (antisense) strand adding nucleotides 5’-3’ creating a primary RNA transcript with the same sequence as the coding strand (sense)

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mRNA strand made in transcription is complementary to _____ and the same as ______

Complements the template strand
Same as the coding strand
** uracil instead of thymine

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Termination phase terminates transcription which it hits which sequence

UAA UAG UGG

Remember on the template strand UAA would be ATT and coding strand would be TAA

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Do page 59 in classroom companion**

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3 types of post transcriptional modification

Does this occur in bacteria mRNA?!

MRNA in bacteria are translated directly into a protein. eukaryotes undergo

5’ cap methyl guanine cap is added to 5’ end protects from degradation by exonucleases
Poly A tail on 3’ end , the string of adenin protects from degradation
Splicing - introns are cleaved and Exxon’s are spliced together by snRNPs

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What is a ribozymes

RNA molecule that can catalyze reactions , one of the few enzymes that’s not a protein

What happens to mRNA after post transcriptional modification

Exons Exit the nucleus into cytoplasm to undergo translation

Start codon

AUG

MRNA nucleotides strung together form the genetic code which has 3 key features

Unambiguous - codes from a specific amino acid Degenerative - an amino acid can have more than one code Universal - all living organisms use the same code except the mitochondria

What are the sedimentation coefficients of prokaryotic and eukaryotic ribosome

Pro - 30 + 50 (70) | Euk - 40 + 60 (80)

Describe translation process

TRNA with methionine enters P site to form initiation site. C end binds to N end of amino acid in a dehydration reaction. That tRNA goes to E site and exits while a new tRNA comes to A site until a stop codon reaches the A site

Ditrection of translation

5’ to 3’ and N to C

Is there proof reading in translation , transcription , replication

No Reduced High and fast

Key differences between prokaryotes and eukaryotes in transcription/translation

Pro - not membrane bound so can occur simultaneously therefore less regulation and control Euk - transcription in nucleus, translation in cytosol

When you come across a membrane bound protein (functions in ER rather than cytosol) how was it created

First couple of amino acids form a signal peptide that is recognized by RNA signal recognition particle that binds and then carries the ribosome complex to SRP receptor protein on the endoplasmic reticulum The N terminus of the peptide is orientated into the lumen (interior) and translation resumes with the peptide growing inside the lumen!

Difference between posttrascriptional control and posttranslational

Transcript - 5’cap, poly A tail, splicing | Translat - how proteins are folded, carbs or lipids added, exported

Silent point mutation

Codon codes for same amino acid

Missense point mutation

Codon codes for different amino acid that may or may not impact the protein

Nonsense

Changes to stop codon resulting in non functional protein

Frameshift

Insertion not in a multiple of 3 alters the reading frame

Nonframeshift mutation

Multiple of 3 nucleotide inserted into gene sequence

Explain what goes wrong that cancer cells form

No apoptosis Proto-oncogene is a normal gene that becomes an oncogene due to a mutation often caused by a carcinogen Loss of tumor suppressor gene

How does DNA become a chromosome

DNA wraps around his tones to form nucleosides which become a solenoid then chromatin which become chromosomes

What is a chromosome

Organized DNA+protein structure in the nucleus | Single double helix of coiled DNA that contains genes

Cell cycle for somatic cells consists of mitosis and interphase , what are the stages of interphase

after mitosis G0 = cell arrest G1 = growth S = 46 chromosomes duplicated into sister chromatids G2 = double check

What is mitosis and what does it produce

Nuclear cell division * no genetic change | 2 genetically identical daughter cells with 46 chromosomes

4 phases of mitosis

Prophase - chromosome condenses, spindle forms Metaphase - chromosomes align Anaphase - sister chromatids separate, cytokinesis begins Telophase - new nuclear membrane forms

What does diploid mean

Cell has homologous pairs

In the nucleus of a human cell there are 46 chromosomes before replication, how many are there after replication

46 chromosomes still!!!! | Refer to duplicates as sister chromatids, this is a very important concept

What is the result of meiosis

Four haploid gametes from a single diploid germ cell

What happens during prophase 1 of meiosis

Homologous chromosome s(same genes) form a tetrad which is held together at the chiasmata where crossing over of genetic material occurs

Product after meiosis 1

Haploid 23 chromosomes / 46 chromatids

3 ways eukaryotes increase genetic diversity

Crossing over in prophase 1 Random assortment in metaphase 1 Fertilization

What is nondisjunction and how serious is it

Failure of chromosome pairs to separate at anaphase resulting in aneuploid cells which is not much of an impact on somatic cells but can be severe in embryogenesis

Monopoly vs trisomy

Mono - loss of single chromosome in zygote - often not viable Tri - addition of chromosome in zygote

See page 90 for differences between mitosis and meiosis

how are dna nucleotides linked

covalent phosphodiester bond formed by dehydration between OH of 3' carbon and the phosphate attached to the 5' carbon