Chronobiology and Sleep: Exam 1 Material

What are the main functions of the nucleus?

DNA storage, transcription and ribosome assembly

What are the main functions of the endoplasmic reticulum (ER)?

synthesis of secreted proteins and lipids, calcium storage

What happens to ribosomes that are free in the cytosol?

translate mRNA into cytosolic proteins

What happens to the ribosomes associated with the ER (rough)?

making proteins bound for organelles, secretion, or the plasma membrane

What is the main function of the golgi apparatus?

after proteins are made in the ER, they go to the golgi for post translational modifications (some of them get released from the cell)

What is the main function of the cytoskeleton?

backbone of the cell, cell motility, and mechanical tasks

What is the main function of the mitochondria?

ATP production and apoptosis regulation

What are the main functions of vesicles?

used in exocytosis, endocytosis, or intracellular traffic

What is the main function of the centriole?

assembly of mitotic spindle

What is the main function of lysosomes?

degradation of macromolecules

What is the central dogma?

DNA is transcribed into mRNA which is translated into proteins

Describe the structure of DNA (what nucleic acids are made of)

phosphate group, deoxyribose group (at 2' there is only H), purine or pyrimidine base

Describe the structure of RNA (what nucleic acids are made of)

phosphate group, ribose group (at 2’ there is an OH), purine or pyrimidine base

Which direction is DNA polymerized?

5’ to 3’ direction connected by phosphodiester bonds

DNA biological characteristics

double stranded helix of nucleotides, 4 nitrogenous bases (adenine, thymine, guanine, cytosine), highly stable and self replicationg, housed in the nucleus of eukaryotes

How many hydrogen bonds are in a GC and AT pairing

GC has 3 hydrogen bonds (energy is about 1.5x more), AT has 2 hydrogen bonds

What is the functional unit of DNA?

genes (about 20,000 of them in the human genome)

What is a gene?

DNA sequence that codes for a protein

What are genes composed of?

start site (MET), exons, introns, stop site

What are exons?

coding regions that will be translated into a proteins (exons are expressed)

What are introns?

non-coding regions that are removed by splicing

What are the UTR (untranslated region) regulatory sequences?

part of the gene that is transcribed but not translated that are located at the 5’ (before the start codon) and 3’ (after the stop codon)

What is a promoter (is not transcribed or translated) ?

regulatory sequence that promotes the expression of the gene (usually 5’/upstream to the gene and initiate transcription)

example: TATA box

What is an enhancer (is not transcribed or translated)?

regulatory sequence that amplify gene expression (usually far away from gene and bring in transcription factors)

Example: Ebox (6 nucleotides 5’/upstream of circadian genes are bound by transcription factors BMAL1 and CLK)

What are promoters and enhancers responsible for?

controlling time and location of gene expression

mRNA (messenger RNA) biological characteristics

single strand of nucleotides that transcribes and transports the info encoded by DNA to generate proteins, 4 bases (adenine, guanine, uracil, cytosine), made in the nucleus and translated in cytoplasm

Describe transcription

DNA in the nucleus is transcribe into pre-mRNA, after splicing and processing mRNA is exported into cytoplasm to be translated into protein

What does transcription allow for?

DNA to be stored safely in the nucleus and alternative splicing (one gene with many messages)

What are the stop codons?

UAA, UGA, UAG

What is the last base in the codon called?

wobble base

What are the additional processing done to pre-mRNA prior to translation?

addition of 5’ cap and poly A tail

Briefly describe the process of translation

tRNA carries AA from cytosol, new AA is added at the a site, empty tRNA is released at the e site

Eukaryotes Characteristics

pre-mRNA splicing, 5’ cap and 3’ poly-A tail, have membrane-bound organelles, have ribosome, have cell membrane

Prokaryotes Characteristics

no pre-mRNA splicing, no mRNA modifications, polycistronic mRNA, no membrane-bound organelles, have ribosomes, have cell membrane