Session #4 AGRI 3409

Flashcards for Genetics Exam 1 Test Prep

What is the central dogma of molecular genetics?

DNA -> RNA (transcription) -> Proteins (translation)

Who is the father of genetics? What did he discover?

Father of Genetics; used pea plants to discover that traits are passed down from parent to offspring by a pair of factors

What is the difference between genes and chromosomes?

Genes reside on chromosomes! A gene is a small section of DNA that contains instructions for a specific trait.

What is the source of all genetic variation?

Genetic MUTATIONS

What is the difference between a diploid and a haploid cell?

Diploid cells have two sets of chromosomes (humans have 2n=46); haploid cells have one set of chromosomes (human gametes have n=23)

If a alien organism discovered in a UFO crash has a diploid number (2n) of 100, what is it's haploid number (n)?

50

What is the difference between a phenotype and a genotype?

Genotype: set of alleles an organisms carries for a specific trait; Phenotype: observable physical trait of an organism

What is a transgenic organism?

An organism with foreign DNA inserted into its genetic code (GMOs)

Describe 2 differences between DNA and RNA.

DNA: Double stranded, contains A, T, C, G. RNA: Single stranded, OH group on the C-2'

How do we refer to the nucleotide triplets that code for a specific amino acid?

Codons

How many different amino acids can be used to create polypeptides?

20

What criteria must a molecule meet to be able to serve as genetic material?

Must be able to replicate, store genetic information, express information by transcription and translation, and be able to mutate

What are the 2 kinds of nitrogenous bases and what are their physical differences?

Purines- 9 member ring; Pyrimidines- 6 member ring

What charge does DNA have and what gives it that charge?

Negative; phosphate group

What bonds link phosphate groups to pentose sugars to form the "backbone" of the DNA ladder?

Phosphodiester bonds

What bonds link nitrogenous bases to form the "steps" of the DNA ladder?

Hydrogen bonds

Who is responsible for publishing the paper which outlines the molecular structure of DNA and in what publication did they publish?

Watson and Crick

What did Chargaff's proposed base composition state?

A=T , C=G , BUT, A+T≠C+G

You are a scientist sequencing the DNA of a new species of rodent found deep in the Amazon rainforest. If you find that 12.5% of the base pairs present in the DNA are Guanine, what is the proposed percentage of Cytosine, Adenine, and Thymine in the genome?

G=12.5%, C=12.5%, A=37.5%, T=37.5%

What is the semi-conservative model of DNA replication?

New DNA Strand = 1/2 old Strand + 1/2 new Strand

What is the most biologically active form of DNA?

B-DNA

What is the only left-handed double helix DNA?

Z-DNA

At what wavelength does PROTEIN absorb UV light?

280 nm

At what wavelength do NUCLEIC ACIDS absorb UV light?

254-260 nm

Describe the function of the following types of RNA.

mRNA: template for protein synthesis; rRNA: structural component of ribosome for protein synthesis; tRNA: carry amino acids for protein synthesis

What is the most abundant form of RNA? What is the least abundant form?

Most abundant: rRNA; Least abundant: tRNA

What is the function of reverse transcriptase?

An enzyme that converts RNA to DNA

What 2 factors can denature DNA?

Heat or stress

What does nucleic acid electrophoresis do?

Separates DNA and RNA fragments by size; smaller fragments travel further in the agarose gel

Which of the following samples have more cytosine/guanine pairs present? species G, E, or C graph

Species C

If we were to stretch out all of our DNA from the chromosomes of 1 somatic cell, how long would it stretch?

2 meter or 6.6 ft

In order to get all of that DNA to fit into the nucleus of ONE cell, what must happen to it? What enzyme is responsible?

DNA must supercoil; topoisomerases

What is a chromatin?

Made up of DNA and proteins (histones) that is uncoil and decondensed

True or False: During interphase, chromosomes are visible within the cell nucleus.

False

True or False: During interphase, chromatin is decondensed and does NOT form visible chromosomes in the cell nucleus.

True

What are nucleosomes? What larger structure do they form?

Nucleosomes are made up of a histone octamer; chromatin

What are the 5 main types of histones?

H2A, H2B, H3, H4, H1

What histone acts as a "spacer" between nucleosomes?

H1

What are histones? What are histone tails?

Histones: positively charged proteins containing large amounts of lysine and arginine; Histone tails: are not packed into folded histone domains with nucleosomes and are potential targets for chemical modification

What are the 3 types of chemical modifications, what enzyme is responsible for each, and what do they do?

Acetylation (Histone acetyltransferase, adds a acetyl group), Methylation (Methyltransferase, Adds a methyl group), Phosphorylation (Kinase, Adds a phosphate group)

True or False: Euchromatin is typically uncoiled and active.

True

True or False: Heterochromatin is typically condensed and inactive.

True

What are pseudogenes and roughly how much of our genome do they constitute?

Non-coding regions of genes that have undergone significant mutational alteration and are not transcribed, 2-10%