Cell Physiology, Part 2: Nucleus, Ribosomes, and Central Dogma

Erythrocytes

Carry O2

Neurons

Fire (action potentials)

Muscle Cell

Contract

Cancer Cells

Grow

The Nucleus

Usually the largest cell component

double-layered nuclear envelope (or membrane)

Contains cell’s genetic material, DNA

DNA Functions

Direct protein synthesis

Serve as genetic blueprint during cell replication

Nucleotides

Deoxyribonucleic acid

Nucleotide function

blueprint for protein assembly

DNA is made from ____

millions of nucleotides

Nucleotide parts

Sugar, phosphate, base

4 bases in DNA

adenine (A), guanine (G), cytosine (C), thymine (T)

What are the nucleotides held together by?

Hydrogen bonds

Base pairing

A with T, C with G

Purines

adenine and guanine

Pyrmadines

cytosine, thymine

What is a gene?

a stretch of DNA that codes for the synthesis of a given polypeptide or protein.

The Central Dogma of Biology

DNA is transcribed to RNA which is translated to protein

Transcription (general info)

Sequence of bases (ACTG) that make up the gene (in the DNA) determines the protein that will be made, ie the amino acid sequence of the protein

How are bases organized in transcription?

triplets

To make protein, the gene first needs to be ____ (actually the process of transcription)

transcribed from DNA to mRNA

What does transcription

RNA Polymerase

Where is Ribonucleic Acid (RNA) produced

the nucleus through transcription of the DNA code by RNA polymerase

mRNA makes up ___

~1.5% of total RNA.

mRNA

coding RNA, codes for proteins

Non-coding RNA

tRNA, rRNA, siRNA/miRNA

tRNA

delivers amino acids to ribosomes for translation

rRNA

component of the ribosome

siRNA and miRNA

regulatory RNAs that silence gene expression by interfering with translation

How is the mRNA code organized

codons, which are complementary to the DNA’s triplet code

Template strand broken into _____, mRNA broken into ______

triplets, codons

What is the different nucleic base in rna?

U (uridine)

A codon codes for an ___

amino acid

Each 3-base codon in mRNA codes for

one amino acid

Ribosomes:

site of protein synthesis as directed by mRNA

Where do you find ribosomes?

rough ER, nucleus, and unattached (free in cytosol)

What are ribosomes made of

rRNA and protein

Endoplasmic reticulum

Elaborate fluid-filled membranous system distributed throughout the cytosol

ER primary function

protein and lipid synthesis

Two types of ER

Rough (protein synthesis)

Smooth (lipid and steroid synthesis, protein modification)

The Leader Sequence (AKA signal sequence)

determines where the newly translated protein will go (ER? mitochondria? Nucleus? Peroxisome?)

Post Translational processing