Week 1 learning goals Flashcards
Characteristics of living things (9)
- organization
- response to environment
- metabolize
- reproduce
- homeostasis
- contain 1 or more cells
- Capacity to grow and develop
- Evolution of populations
- DNA
Cell
basic unit of life
smallest unit with the capacity to live and reproduce, independently or as part of a multi-cellular organism
when and who invented the 1st microscope?
In 1595 Z. Jansen invented the 1st microscope
What and when were Robert Hookes contributions to the history of cells?
1665 - Robert Hook wrote Micrographia in which he….
coined the term “cell”
wrote about the compartments that he had view of a cork which he called cells based off monk’s living quarters
What were the limitations of cell biology after 1665?
- Optical instruments had limited resolving power of microscopes and lacked detail
- Their way of thinking - they were less interested in the why
The 17th century was known as the ….
Age of Observation - descriptive science was used “ look at this”
Explain the Advances in Optics in the 1830’s
- Lens quality improved
2. Development of the compound microscope occurred by improving both magnification and resolution.
Who dis covered the Nucleus
Robert Brown- a Scottish botanist who observed plant cells and plant fertilization
Explain Robert Brown’s observations
Brown noticed that every plant cell gad a rounded structure within
He called this structure the nucleus this is latin for kernel
List the accepted cell theory (3)
- Cell is the unit of structure of physiology + organization in living things.
- The cell retains a dual existence as a distinct entity and a building block in the construction of organisms
- Cells arise from preexisting cells
Which postulate of the accepted theory was disputed?
The third postulate which was written by Schlieden and Schawann originally stated “ Cells arise spontaneousluy but was correct by Virchow in 1885 to “ Cells arise from preexisting cells”
Who’s is Virchow?
A German scientist who changed the 3rd postulate of the cell theory
Why did Virchow change the third postulate?
Based off
- Brown’s discoveries of the nucleus
- Lousi Pasteur’s discoveries about ‘germs’
Explain Scala Naturae
” Ladder of complexity”
classification of scheme outlined in aristotlles history of animals
- all matter organized is decreed by god
- definitions of vertebrates and inveratebes are still used today
Most early classifications like this one is based primarily on physical and spiritual characteristics
What are the domains of life and what do they include?
Bacteria - Prokaryotes
Archaea - Prokaryotes and many extemeophiles Eukaraya - eukaryotes including protists, plants, fungi and animals
Who is credited with redrawing the tree of life into 3 domains
Poineered by Carle Woese and George Fox in the 1970’s by redrawing the phylogenetic relationships based on analysis of the rRNA sequences which resulted in the five kingdoms
What were the kingdoms in the 1700’s and who wrote them?
2 kingdoms under Plant or Animal
Bacteria = plants
classification was written by C. Linneaus
What were the kingdoms in the 1960’s?
Monera (prokaryotes) Protista Plantae Fungi Animalia
Why were rRNA gene sequences used for to analyze phylogenetic relationships?
- rRNA is present in all living things
- rRNA sequences change very slowly overtime so any slight change would point to evolutionary change.
- conserved regions enable easy in vitro replication
- relationships of evolution
What information did we learn from the analysis of the rRNA gene sequences pioneered by Woese and Fox?
- 2 separate groups of prokaryotes - Bacteria and archaea domains
- Also suggests that eukaryotes and archaea are more closely related that to each other than bacteria
- allowed better understanding of how protists should be organized phygenetically
- revealed how incorrect it was to classify them all together in 1 kingdom
- some protists are not even closely related at all
What is a protist? Why is it no longer correct to classify all protists together into one phylogenetic group?
A protists is a diverse grouping of eukaryotic organisms
- Many diverse lineages of various eukaryotic organisms - they can be unicellular or multicellular
Are viruses considered living organisms?
No because…
- They cannot reproduce w/o a host cell
- They also do not meet the other cellular requirements of growth, response to environment, metabolism, homeostasis and have 1 or more cells
Does a prokaryote or eukaryote have the following: nucleus ?
Prokaryote: absent
Eukaryote: present
Does a prokaryote or eukaryote have the following: internal complexity?
Prokaryote: Lacking
Eukaryote: Extensive membrane bound organelles
Does a prokaryote or eukaryote have the following: size?
Prokaryote: very small - avg. size 1-4 micrometers
Eukaryote: avg size 10-100 micrometers
Similarity of plant and animal cells?
share many of the same sub cellular structures
Four structural features shared by all cells
- Surrounded by a lipid based plasma membrane
- Metabolic machinery
- DNA as hereditary info
- Ribosomes as protein synthesizing machinery (Central dogma: transcription & translation)
Metabolic machinery
enzymatic pathways convert energy into a usable form
Micrometers
used when expressing the size of cells and larger organelles
Nanometers and Angstroms
commonly used to express the size of molecules and smaller sub cellular structures EX: bacterial ribosome, DNA
Dalton
Da
unified atomic mass unit
1/12 C = 1.66*10^24 g
commonly used to describe the size of proteins
EX: Hemoglobin (Human) - 68000 Da –> 68 kilodaltons (kD)
Why is cell size limited ?
- resource availability EX: nutrients, space
- SA to volume ration KEY REASON
- ratio is critical to cell metabolism
Effects of SA to volume ratio
if the volume grows proportionately more than SA it will lead to problematic change of substances between cell and environment which affects localized concentrations of molecules .
This in turn affects diffusion rate of molecules –> affects rates of chemical rxns… slows rxn rates are not good for living things
Explain the strategies cells/ organisms can use to overcome the limitations imposed by SA:V constraints.
- Growth stops
- Membrane folding
- Active Transport
- Multicellularity
Describe how stopping of growth helps overcome the limitations imposed by SA:V constraints
The cells enter the G0 phase
At this phase cells become quiescent or terminally differentiated
- withdraws from the cell cycle results in the stopping of cell growth
Describe how membrane folding helps overcome the limitations imposed by SA:V constraints
Membrane folding increases the amount of surface area
- Membrane folding allows more nutrients to be effectively absorbed.
Seen in both eukaryotes and prokaryotes.
EX: brush border cells of intestinal epithelium (microvilli)
Describe how active transport helps overcome the limitations imposed by SA:V constraints
Active process = expenditure of E by the cell
EX: Not relying on simple diffusion
EX: Transportation of cargo by specialized carrier proteins
Describe how multicelluarity helps overcome the limitations imposed by SA:V constraints
More cells will increase the SA
- SA:V sets an upper limit on cell size
- The only way to get larger cells to cooperate
- Thought to be the driving force behind the evolution go multicelluarity
How to calculate Surface area of cells
HW#of sides * # of cells
Epithelial cell
any tissue that is lining a surface (not limited to the plasma membrane ) EX: Intestines
What is Cell Fractionation
process to separate sub cellular components
How organelles are studied
List in order the steps of cell fractionation
Cell Lysis
Homogenization
Centrifugation
Describe Cell Lysis
Cells are broken open to get the contents of cytoplasm
- occurs by exposure tio chemicals, enzymes or sound waves
Describe Homogenization
sub cellular contents are blended together –> “cell soup”
EX: Milk blends fat + liquid phase
Describe Centrifugation
Use of centrifugal force to differentially sediment a heterozygous mixture
- Each subcellular component has different densities so they will form different layers
