Cell bio

up to midterm 1

cell is the __

basic unit of biology

Cells are constantly changing; they have the capacity to __, __, and become __

grow

reproduce

specialized

three strands of biological inquiry weave into modern cell bio

Cytology, Biochemistry and Genetics

Cytology

focuses on cellular structure and emphasizes optical techniques

Biochemistry

focuses on cellular structure and function

Genetics

focuses on information flow and heredity and included sequencing of the entire genome (all of the DNA) in numerous organisms

Robert hooke (1665), what did he observe and what did he call it and why

observed cork under microscope- dead plant tissue

first named cells meaning “little room”

what were hookes observation limited by

low magnification power (30X enlargement)

Who produced better lenses that magnified up to 300X in 1673

Antonie Van Leeuwenhoek

what did Antonie Van Leeuwenhoek call the first observed moving single cells

animacules

what were the 2 factors that restricted progress in early cell bio

1- microscopes had limited resolution or resolving power(ability to see fine detail)

2- descriptive nature of cell bio, focus was on observation with little emphasis on explanation

when were compound microscopes used, and describe them

by the 1830s

2 lenses, increased magnification and resolution

using a compound microscope Robert Brown identified the ____ inside a ___ cell

nucleus

plant

using a compound microscope Theodor Schwann identified the ____ inside a ___ cell

nucleus

animal

cell theory and who created what part

1839- Schwann

• all organisms consist of one or more cells

• the cell in the basic unit of structure of all organisms

1855- Virchow

• all cells arise from preexisting cells (he must have observed cell division)

what evidence led scientists to develop the basic principles of cell theory? note how tec played a role in its development

observing a variety of species/organisms under a microscope

had simple microscopes so observations were limited, ad the microscopes developed so did cell theory

difference between simple and compound microscope

simples- 1 lens, 30X magnification

compound- 2 lenses, up to 300X magnification

what problem have microscopes been helpful with

the small size of cells and their components

how small is a micrometer(um) and what is used to see

one millionth of a meter (10^-6 m)

used to view cells and bacterium

how much larger are plant and animal cells than bacterial cells

10-20 times larger

____ are comparable to bacterial cells in size

organelles

how small is a nanometer(nm) and what is used to see

one billionth of a meter (10^-9m)

used to measure molecules and subcellular structures that cant be seen in the light microscope like organelles and ribosomes

how small is an angstrom (Å) and what is used to see

0.1 of a nm (~size of a hydrogen atom)

measures bonds and atoms (within proteins and DNA molecules)

what was the earliest tool of cytologists

light microscope

the light microscope allowed identification of ___, ___ and ___ within cells

nuclei, mitochondria and chloroplasts

in a light microscope, what kind of light passes through a specimen

white light

what is another word for light microscope

brightfield microscopy

what kind of samples are used within the light microscope

samples are dead, alive, fixed and stained

what did the microtome allow

and what began to be used around the same time, what time was this

allowed preparation of very thin slices of samples, 4-10 um thick sections

dyes for cells began to be used around the mid-1800s

what is the limit of resolution

how apart objects must be to appear distinct

sharpness limit

what is resolving power

ability to see fine detail

what did dyes lead to

• improved the limit of resolution

• the small the microscopes limit of resolution the greater the resolving power

what are paraffin embedded tissues and what ability do they provide

biological tissue that has been preserved, dehydrated, and then embedded in a block of paraffin wax so it can be sliced very thinly for microscope slides

they provide the ability to study subcellular structures

what did the development of coal tar-derived dyes permit

they permitted the differential staining of a host of subcellular structures (parts inside the cell)

initially what were single stains used to facilitate

the study of otherwise transparent cells

what did the dual staining of H____ and E______ staining allow

hematoxylin and eosin

acidic = blue

basic = pink

immunostaining allows labelled __ to reveal the presence of specific molecules

antibodies

explain immunohistochemistry schematic

1- primary antibody= binds to the protein that is of interest (antigen)*

2- secondary antibody already has an enzyme(chemically conjugated) and ONLY binds to the primary antibody (antigen)

3- The substrate of the enzyme will give the colour

4- where the colour is that’s where the protein of interest is

*what the antibody binds to

what quality is based of the quality of the lens of microscopes

optical resolution

what type of microscope is used when dissecting and has low magnification

dissecting light microscope

what light microscope is used to look at cells and bacteria and has a high magnification

compound light microscope

what light microscope is used to look at live cells with high magnification

inverted compound light microscope

what can we used to increase contrast in a basic light microscope

dif types of illumination

what type of illumination is this

brightfield

little contrast without staining

what type of illumination is this

polarized light

cancels out dif wave lengths of light

what type of illumination is this

darkfield

only scattered light is viewed

what type of illumination is this

phase contrast

phase rings scatter light to increase contract

live cells

what kind of light do differential interference contract microscopy use

polarized

phase contrast and differential interference contrast microscopes exploit dif in ____ of ___ passing through a structure with a ______ ____ different than the surrounding medium. It makes it possible to see _____ cells clearly

phase

light

refractive index

living

refractive index

how much a material slows down and bends light when it passes through a medium

each part of the cell will have dif refractive intext

fluorescence microscopy detects _______ ___ or labels, to show _____ of substances in the cell

ex- _____, ____

fluorescent dyes

location

immunostaining

DAPI

a fluorescent dye that binds strongly to adenine-thymine-rich region on DNA

fluorophore

molecule that absorbs light at one wavelength (the excitation light) and then emits light at a longer wavelength (the fluorescence you see)

fluorescence microscopy allows detection of ___, ___ _____ or _____ that have been made fluorescent by binding to _____

proteins

DNA sequences

molecule

antibodies

antibody

protein that binds a particular target molecule called an antigen

the antibody can be coupled to a fluorescent ______, which emits _______ whenever the target molecule is bound by the _____

molecule

fluorescence

antibody

_____ ______ protein (GFP) can also be used to study the ____ and ______ distribution of ______ in a ______ cell

Green fluorescent protein

temporal (time) and spatial (space and location)

proteins

living

confocal microscopy

takes photos at dif subsections to remake 2D and 3D images, using a laser beam

digital video microscopy

uses cameras to collect digital images

does confocal microscopy need fluorescence

usually does not its not necessary

what light does fluorescence microscopy absorb and what one does it reflect

absorbs ultraviolet radiation

emits visible light

what are the limits to the resolving power of each class of microscope based on wavelength

human eye

light microcopy

electron microscope

human eye ~0.1mm

light microcopy ~0.0001mm (0.1um)

electron microscope ~0.0000001mm (0.1 nm)

cryo electron microscopy

biological samples are rapidly frozen and then viewed with an electron microscope. The freezing preserves the sample in a near‑natural state without needing chemical fixation or staining

looked under the microscope in cold conditions

limit of resolution

how far apart objects must be to appear as distinct

the small the microscopes limit of resolution the greater its _____ ____

resolving power (ability to see fine details)

low frequency means _____ resolution

high frequency means _____ resolution

poor

good

the good resolution for a light microscopy is related to the _____ ______ of ____

physical nature of light

for visible light the limit of resolution is about ____-_____ ___

200-350 nm

when was the electron microscope developed and what does it use rather than light

1930s

a beam of electrons

how much better is the resolution of the electron microscope compared to the light microscope

100 times better

what is the limit resolution of the electron microscope

0.1-0.2 nm

how much better is the magnification of electron microscopes compared to light microscopes

up to 100 000x

in scanning electron microscopy (SEM) the ____ of a specimen is scanned by detecting ______ _____ from the outer surface

surface

electrons deflected

what are two visualizations of specialized electron microscopy

visualization of specimens in 3 dimensions

visualization of individual atoms

what did Fredrich Wohler do and when

1828

showed that a compound made in a living organism- urea- could be synthesized in the lab

what was though about living organisms prior to Fredich’s work

prior to his work it was thought that living organisms were unique and not governed by the laws of physics and chemistry, that organic molecules could only be made by living organisms

“organic” molecule could be made from inorganic chemicals = vitalism

what does vitalism mean

that organic molecules could NOT be made from inorganic ones because living things supposedly had a special “vital force” that non‑living matter lacked

what did louis paster show and in what year

1860s

showed that yeast could ferment sugar into alcohol

what did Eduard Buchner show and in what year

1897

showed that yeast extracts could ferment sugar into alcohol providing that cells was not a requirement

pasteur but mainly buchner lead to what discovery, and what are they

enzymes = biological catalysts

what did gustav Embden, Otto Meyerhof, Otto Warberg and Hans Krebs describe the steps of

steps of glycolysis (the embden-Meyerhof pathway) and the Krebs cycle

what did Fritz Libmann show

that adenosine triphosphate (ATP) is the principle energy storage compound in most cells

what did Melvin Calvin and his colleagues elucidate

the Calvin cycle

radioactive isotopes

to trace the fate of specific atoms and molecules

what did radioactive isotopes led to the elucidation of

the Calvin cycle

subcellular fractionation

uses centrifugation to separate/isolate dif structures and macromolecules

ultra centrifuges

capable of very high speeds (over 100 000 revs per min)

chromatography

technique to separate molecules from a solution based on size, charge of chemical affinity (chem properties)

electrophoresis

uses an electrical field to move proteins, DNA, or RNA through a medium based on size and chrage

mass spectrometry

used to determine the size and composition of individual proteins