Exam 1 Flashcards
biomolecules
The molecules of living organisms
organic molecules
(carbon-containing compounds
Urey and Miller
the first cells had to arise from
the first cells had to arise from
nonliving chemicals, inorganic substances
Earth’s age
The Earth came into being about
4.54 billion years ago
4 stages of the Origin of life
- organic monomers
- Organic polymers
- Protocells or protobionts
- Protobionts acquire ability to self-replicate
explain Stage 1: Evolution of monomers
whatr the hypothesis for how monomers evolved?
Several hypothesis for how monomers evolved
1. monomers came from outer space
2. monomers came from reactions in the atmosphere
- molecules could be formed in the presence of outside energy sources using atmospheric gases
3. monomers came from reactions at hydrothermal vents
Miller and Urey Experiment
Stanley Miller and Harold Urey
conducted an experiment to test the
Oparin-Haldane hypothesis:
Showed that gases (methane,
ammonia, hydrogen, and water) can
react with one another to produce
small organic molecules (amino
acids, organic acids)
Strong energy sources
Rainfall would have washed organic
compounds from the atmosphere
into the ocean.
They would have accumulated in the
ocean, making it an organic soup.
Chemical Evolution at hydrothermal vents
Hydrothermal vents are chemical hot springs found
in seafloors.
- They might have seeded life on Earth about 4 billion
years ago. - Conditions including a 158°F (70°C) temperature
are just right for chemical reactions responsible for
the formation of amino acids and primitive
membranes.
Explain stage 2: evolution of polymers
describe how polymers form and the 3 hypotheses
In cells, monomers join to form
polymers in the presence of enzymes.
A process known as polymerization.
Iron–Sulfur World Hypothesis:
It suggests organic molecules reacted with amino
acids to form peptides in the presence of iron-nickel
sulfides.
Protein-First Hypothesis
It assumes that protein enzymes arose first.
DNA genes came afterwards.
RNA-First Hypothesis
It suggests only RNA was needed to progress
toward the formation of the first cell or cells.
Some viruses have only RNA genes.
DNA genes would have come afterward.
Stage 3 evolution of Protocells
define proteinoids
define protocells
describe strucutre of protocells
Before the first true cell arose, there
would have been a protocell or
protobiont, the hypothesized
precursor to the first true cells
A protocell would have an outer
membrane and carry on energy
metabolism
Proteinoids are small polypeptides
with catalytic properties
Define and describe proteinoid and liposomes
When proteinoids are placed in
water, they form microspheres,
structures made of proteins with
many properties of a cell
If lipids are made available to
microspheres, lipids become
associated with microspheres,
producing a lipid-protein membrane
Lipids placed into water form cell-
sized double-layered bubbles called
liposomes
They may have provided the first
membranous boundary
liposomes
Lipids placed into water form cell-
sized double-layered bubbles called
liposomes
stage 4 : evolution of a self-replication system
Describethe 2 main hypotheses
2 main hypothesis
RNA - first
The first cell would have had an RNA gene that
directed protein synthesis.
Reverse transcription could have led to DNA.
RNA was responsible for both DNA and protein
formation
RNA - DNA -RNA - Protein
Protein First
The protocell would have developed a plasma
membrane and enzymes.
Then, DNA and RNA synthesis would have been
possible.
After DNA evolved, protein synthesis would have been
carried out according to the central dogma.
After DNA formed, the genetic code had to
evolve
cell
basic unit of biology
what 3 sciences converged to make cell bio
cytology
genetics
biochem
who named cells “cells”
Robert Hooke - 1665
he observed compartments formed by cell walls of dead plant tissue
he called these compartments cells
what two factors restricted progress in early cell biology
Microscopes had limited resolution, or
resolving power (ability to see fine detail)
compound microscope
1830s
had two lenses
improved magnification and resolution
could see structures 1um clearly
Robert Brown
identified the nucleus inside plants cells using the compound microscope
Mathias Schleiden
concluded that all plant
tissues are composed of cells
thomas Schwann
concluded that all ANIMALS
tissues are composed of cells
postulated the cell theory
Cell theory
Postulated the cell theory in 1839
1. All organisms consist of one or more cells.
2. The cell is the basic unit of structure for all
organisms
Rudolf Virchow
what year?
added to the cell theory in 1855
3. all cells arise only from preexisting cells
cytology
focuses mainly on cellular structure and
emphasizes optical techniques
biochemistry
focuses on cellular structure and
function
Genetics
focuses on information flow and heredity
and includes sequencing of the entire genome (all
of the DNA) in numerous organisms
Microscopy
crucial in helping cell
biologists deal with the
problem of small size of
cells and their
components
Micrometer
(μm), also called the micron, is
one millionth of a meter (10 -6 m
Size of bacterial cells vs plants vs animal
Bacterial cells are a few μm in diameter, whereas
cells of plants and animals are 10–20 times larger
Organelles are comparable to bacterial cells in size.
nanometer
The nanometer (nm) is used for molecules and
subcellular structures too small to be seen in the
light microscope
The nanometer is one-billionth of a meter
(10-9 m)
angstrom (Å)
The angstrom (Å), which is 0.1 nm, equals about
the size of a hydrogen atom
It is used in cell biology to measure dimensions
within proteins and DNA molecules
light microscope
earliest tool of
cytologists
allowed identification of nuclei, mitochondria, and
chloroplasts within cells
light microscopy is also called
brightfield
microscopy because white light is passed directly
through a specimen
improvements in Microscopy
microtome -mid-1800s) allowed
preparation of very thin slices of
samples
dyes - A variety of dyes for staining cells
began to be used around the same
time
These improved the limit of resolution (how far apart objects
must be to appear as distinct)
the smaller the microscope’s limit of resolution, the…
greater its
resolving power (ability to see fine details)
Specialized Light Microscopy ( list the types)
Phase-contrast (PC) microscopy
Differential interference contrast (DIC) microscopy
Fluorescence microscopy
Confocal microscope
Contrast Microscopy
Phase contrast and
differential interference
contrast microscopy
make it possible to see
living cells clearly
The phase of transmitted
light changes as it passes
through a structure with a
different density from the
surrounding medium
These types of microscopy
enhance and amplify these
slight changes
Fluorescence Microscopy
allows
detection of proteins, DNA sequences, or
molecules that have been made
fluorescent by binding to antibodies
( see slides for more)
antibody
protein that binds a particular
target molecule, called an antigen
GFP
Green fluorescent protein (GFP) can be
used to study the temporal and spatial
distribution of proteins in a living cell
Confocal microscopy
uses a
laser beam to illuminate a
single plane of a fluorescently
labeled specimen
Digital video microscopy
Digital video microscopy uses
video cameras to collect digital
images Microtubules in cultured cells (M. Engelke)
limit of resolution
refers to how far apart
objects must be to appear as distinct
resolving power
ability to see fine details
The resolution for a light microscope is related to
the physical nature of light
for visible light, the limit of resolution is about
200-350 nm
Electron Microscopy
The electron microscope, which
uses a beam of electrons rather
than light, was a major
breakthrough for cell biology
limit of resolution of electron microscope
about 100 times
better than light microscopes
electron microscopy magnification is
is much higher
than light microscopes—up to
100,000×
TEM
transmission electron microscopy - electrons are transmitted through the specimen
SEM
scanning electron microscopy (SEM), the
surface of a specimen is scanned by detecting
electrons deflected from the outer surface
Friedrich Wöhler
1828
showed that a compound made
in a living organism could be synthesized in the lab
Louis Pasteur
(1860s)
showed that yeasts could
ferment sugar into alcohol
The Buchners
1897) showed that fermentation could occur with yeast
extracts
enzyme
biological catalyst
Early biochem
fermentation pathways early 1920-1940s
Glycolysis - mulitple ppl
Krebs - hans krebs
ATP - Fritz lipmann
Calvin Cycle - Melvin Calvin
Subcellular fractionation
uses centrifugation to
separate/isolate different structures and macromolecules
Ultracentrifuges
are capable of very high speeds (over
100,000 revolutions per minute; rpm
Chromatography
techniques to separate molecules
from a solution based on size, charge, or chemical affinity
Electrophoresis
uses an electrical field to move
proteins, DN A, or RN A molecules through a medium
based on size/charge
Mass spectrometry
is used to determine the size and
composition of individual proteins
Genetics
Study of inheritance of characteristics from generation to generation
19th century =
discovery of the gene
Gregor Mendel
experimentation with peas which lead to the understanding of heredity factors from parents to offspring
Heredity factors are now known as
genes
mitosis
cell division
( knaned by walther Flemming
Who formulated the chromosome theory
Morgan, Bridges, Sturtevant
chromosome theory
proposing that Mendel’s hereditary factors are located
on chromosome
Friedrich Mischer
1869
first isolated DNA which he called nuclein
components of DNA
4 different nucleotides ( 1930s)
20 different amino acids = protein
DNA as the genetic material - 1940
one gene - one enzyme concept
Beadle and Tatum formulated the one gene–one enzyme
concept (each gene is responsible for the production of a single
protein)
who proposed the Double Helix model
Watson and Crick, with assistance from Rosalind Franklin, proposed the double helix model for DNA structure (1963)
who proposed the central dogma
Crick: central dogma of molecular bio
DNA ( transcription) - RNA ( translation) - protein
What are the three kinds of RNA molecules what what do they do?
mRNAs (messenger RNAs): translated to produce protein
rRNAs (ribosomal RNAs): components of ribosomes
tRNAs (transfer RNAs): bring the appropriate amino acid for protein synthesis
what are the exceptions to the central dogma
viruses with RNA genomes
reverse transcriptase
an enzyme that uses viral RNA to synthesize complementary DNA
recombinant DNA tech
restriction enzymes cut DNA at specific places, allowing scientists to create recomb. DNA molecules w/ DNA from different sources
DNA cloning
the generation of many copies of a specific DNA sequence
DNA transformation
process of introducing DNA into cells
sequencing DNA
DNA sequencing methods are used routinely for rapidly determining the base sequences of DNA molecules. It is now possible to sequence entire genomes (entire DNA content of a cell).
Bioinformatics
Comp sci & biology merged to interpret enormous amounts of sequencing and other data
Numerous bioinformatic tools are publicly available through NCBI (National Center for Biotechnology Information)
High-throughput methods allow for dramatic increases in the speed of molecular analysis
Expression levels of hundreds or thousands of genes can be monitored simultaneously
Ex: DNA Microarray Assay
CRISPR genome editing stands for
CRISPR = Clustered Regularly Interspaced Short Palindromic Repeats
see slide/come back to card
CRISPR is used as
a tool for genome editing
CRISPR was discovered as a
prokaryotic defense against
viral infection
Biological facts
Facts are provisional, dynamic and subject to change
a “fact” is an attempt to state our best current understanding of the world, based on observations and experiments
testing
Scientists seek to prove the null hypothesis, which is opposite to their hypothesis
The certainty of a particular hypothesis is strengthened when multiple attempts fail to confirm the null hypothesis
Experiments Test Specific Scientific Hypotheses
(idk how to make this a question)
First read peer reviewed sources, then formulate hypothesis
This may take the form of a model, which appears to be a reasonable explanation for the phenomenon
model organism
a species widely studied, well characterized, & easy to manipulate
Each has particular advantages, useful for experimental studies
Much of our knowledge is based on research using few organisms