Introduction to Cells Flashcards
Cell Theory
The cell is the basic organizational unit of life
All organisms are comprised of 1 or more cells
Cells arise from pre-existing cells
Prokaryote
No nuclei
Single-celled (can live in chains or communities)
Bacteria and Archaea (live everywhere)
Eukaryote
Nuclei (membrane-bound nucleus)
Single-celled (Ex. Yeast) or multicellular
Plants, fungi, animals, humans
Origins of Mitochondria (and Chloroplast)
Fossil evidence suggests that prokaryotes arrived/evolved first.
Prokaryotes and eukaryotes share many similar characteristic, thus we believe that they could not have arose separately.
Symbiotic relationship; endosymbiont theory; entangle-engulf-endogenize theory
Note: we do not really know how it happened
Ectosymbiont
Live outside of their hosts’ cells
Endosymbiont Hypothesis
some of the organelles in eukaryotic cells were once prokaryotic microbes
Endosymbiont Hypothesis Support/Proof
Mitochondria and chloroplast have remnants of their own genomes and their genetic systems resemble that of modern-day prokaryotes
Mitochondria and chloroplasts have kept some of their own protein and DNA synthesis components and these resemble prokaryotes too
Membranes in mitochondria and chloroplasts often similar to those in prokaryotes and appear to have been derived from engulfed bacterial ancestors
What are the general attributes of Model organisms?
Rapid development with short life cycles
Small adult (reproductive) size
Readily available (collections or wide-spread)
Tractability – Ease of Manipulation or modification
Understandable Genetics
Model Organisms
A living thing selected for intensive study as a representative of a large group of species.
Central Dogma
Original model for information flow (we now know it is far more complicated that this)
DNA —(transcription)— RNA — (Translation)— Protein
DNA
a cells complete set of genetic information is the genome, that includes the mitochondria DNA
The nuclear genome may mean just the nucleus DNA.
Trasncriptome
All the RNA present in a cell at a given point in time. Constantly changing (unlike the genome); lets us know the genes of a species and their sequences
Proteome
All the proteins in the cell at given time. Changing all the time; the entire set of proteins that is, or can be, expressed by a genome, cell, tissue, or organism at a certain time.
Interactome
All the protein-protein interactions in a cell at a given point in time. The set of all molecular interactions in cells, especially in the context of protein-protein interactions; feeds information to the metabolome
Metabolome
The set of all the metabolites in a cell at a given times. Effects the genome, transcriptome and Proteome; complete set of low molecular weight compounds in a cell at a given time
Phenome
comprised of everything above it in the photo, together with the observable characteristic (phenotypes) of the organism/cell
Infromation Flow
This is the connection between RNA, DNA and Protein
DNA, RNA and proteins are synthesized as linear chains of info with definite polarity (there is directionality to the way the information is being organized, because one side is 5’ and the other is 3’, the bottom is 3’ to 5’, so they are oppositely parallel)
Info in RNA sequence is translated into an AA (amino acid) sequence via a Genetic Code which is essentially Universal among all species
Nucleic Acids
The genetic material in a cell (aka organisms blueprint); basically telling the cell all the instructions.
DNA = Deoxyribonucleic acid
RNA = Ribonucleic Acid
The 3 parts of Nucleotides
Pentose Sugar (scaffold for base); is the connector between the base and phosphate group
Nitrogenous base (varies)
Phosphate group (backbone; 1,2, or 3 Phosphate groups)
DNA bases
G, C, A, T
RNA Bases
G, C, A, U
Nucleoside monophosphate
Sugar + base + 1P
Nucleoside diphosphate
Sugar + base + 2P
Nucleoside Triphosphate
Sugar + base + 3P
DNA is synthesized from
Deoxynucleotide triphosphates, aka dNTPs
RNA is synthesized from
ribonucleoside triphosphates, aka NTPs
Nucleosides are linked by
phosphodiester bonds
Electrostatic Attraction
include ionic bonds, attractions between oppositely charged molecules; happen within and between larger molecules. Especially strong in the absence of water (not possible in cells, relatively weak)
Hydrogen Bonds
weaker than covalent bonds, important for intermolecular bonds and structure (water). Initially and individually not strong, but the more of these you have the stronger it is.
Usually includes an H+.
Van der Waals Attraction
fluctuation in the distribution of electrons, causes a flickering dipole. Are not weakened by water.
Hydrophobic force
all hydrogen bonding with hydrophilic things, pushing things that are non-polar out of the water and out of the bonding network.
Base pairing
- Holds the DNA double helix together
- A-T is connected by 2 H-bonds
G-C is connected by 3 H-bonds
Purines
G, A
2 rings
Pyrimidine
A, T, U
1 ring
Forces that keep DNA strands together
- Hydrogen bonds
- Hydrophobic Interactions
- Van der Waals attractions
DNA has a ____ charge along its___ so it is quite___
Negative, backbone, hydrophilic
Why are bases inside?
Bases are in the middle because H+ bonding bases are non-polar, so they are being pushed towards the middle (away from the water/hydrophilic conditions)
5’ groups is ____
Phosphate group (-PO_4)
3’ group is
Hydroxyl group (OH)
Central Dogma (with DNA, RNA and protein)
In every cell, long polymer chains of DNA are made from the same set of four monomers (nucleotides), strung together in different sequences like the letters of an alphabet. DNA encodes information (info direct assembly of proteins)
The information encoded in these DNA molecules is transcribed in RNA.
RNA is translated into protein.
Proteins in DNA replication and the central dogma
Proteins catalyze the replication DNA and it’s transcription into RNA and they participate in the translation of RNA into proteins. They also catalyze many other chemical reactions that keep the self-replicating system (and others) running.
Genome
The entire sequence of nucleotides in an organism’s DNA. Provides a genetic program that instructs a cell how to function.
Note: Different cells express different genes (produce some RNAs and proteins but not others)
What are the three main domains
Cell and organism types
Eukaryote, Bacteria, and Archea
Cytosol
Is the part of the cytoplasm that is not contained within the intracellular membranes.
It is the largest single compartment
Contains a host of large and small molecules
Behaves like a water-based gel
Cytoskeleton
A crisscrossed by long, fine filaments (is not a structureless soup) . A system of protein filaments.
Actin filaments (thinnest); serve as a cental part of the machinery responsible for muscle contraction. They are abundant in all eukaryotic cells but occur in especially large numbers inside muscle cells
Microtubules (thickest filament); have the form of minute hollow tubes. Are found in dividing cells, helping pull the duplicated chromosomes apart and distributing them to the daughter cells.
Intermediate filaments (intermediate thickness); serve to strengthen most animal cells.
Filaments + proteins form a system of girders, ropes, and motors that give the cell its mechanical strength, contols its shape and drives/guides its movements.
Bacterial and Molecular model organism
E. Coli
Simple Eukaryote Model Organism
Brewer’s Yeast
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Model Plant
Arabidopsis
Provides insight into cell and molecular biology, specifically the mechanisms that enable plants to grow
Model Animals (vertebrates)
Worms, flies, mice, and fish
Sometimes humans too.
Gene Expression
the process by which the nucleotide sequence of a gene is transcribed into the nucleotide sequence of an RNA molecule and then, translated into the amino acid sequence of a protein.
