(1) Cell Biology Flashcards
Outline cell theory
Proposed by Theodore Schwann
in 1839
1) All organisms are made of cells
2) Cells are the basic units of life
3) Cells come from pre-existing cells
History of cell theory
1626: Redi postulated that living things do not arise by spontaneous generation
1655: Hooke describes “cells” in cork
1674: Leeuwhenhoek discovers single celled organisms (prozos and bacteria)
1805: Oken states “all living organisms orginate from and consist of cells
1838: Schwann and Schleiden propose cell theory
Evidence for cell theory
1) All organisms are made of cells
→Microscope
2) Cells are the basic units of life
→ Microscopes were used to examine tissues, any part smaller than a cell (for example, any organelle) is not capable of independently carrying out all of the characteristics of life
3) Cells come from pre-existing cells
→ Miller-Urey Expirement
Functions of life
Movement: internally or externally
Reproduction: asexual or sexual
Growth: change shape and size
Respiration: use substances from the environment for energy
Excretion: removal of waste
Nutrition: exchanges materials from the environment
Sensitivity: respond and interact w environment
Calculating volume, surface area and ratio of a cube
Volume: BxHxW
SA: BxHx6
Ration: Surface area/ volume
Compare the relative size of:
viruses
molecules
bacterium
organelles
cell membrane thickness
plant cell
animal cells
molecules 1nm
cell membranes 10nm
virus 100nm
bacterium 1um
animal cell 1 um
plant cell 10um
organelles µm
Calculate linear magnification and scale
linear magnification: drawing/object
scale: object/drawing
State the importance of the SA/Volume ratio as a factor limiting cell size
-increase in volume = increase in SA
- rate of material exchange is proportional to SA
- rate of metabolism proportional to volume
multicellular organisms show emergent properties. elaborate.
Emergent properties are properties that become apparent and result from various interacting components within a system but are properties that do not belong to the individual components themselves
In multicellular organisms: Cells may be grouped together to form tissues. Organs are then formed from the functional grouping of multiple tissues.
Cells in multicellular organisms differentiate to….
Carry out different specialized functions by expressing and masking certain genes.
Stem cells can retain the capacity to _______ and have the ability to ________.
divide
differentiate along different pathways
Therapeutic use of stem cells
Stem cells can be used to replace damaged or diseased cells with healthy functioning ones
Osmosis
The passive movement of water/something across a semipermeable membrane
phagocytosis, pinocytosis, exocytosis
- eat large cells and particles
- drink waters and liquids
- expel
isotonic value
when cells and environment solute concentrations are equal
Parts of a plant cell
cell wall: surrounds plasma membrane
plasma membrane: protects cell
pilli: help attach cell to surfaces
cytoplasm: medium for chemical interactions
nucleoid: controls activity of cell and reproduction
ribosome: makes protiens
Compare and contrast the structure of eukaryotic and prokaryotic cells
EUKARYOTIC
- naked DNA
- circular DNA
- no nucleus
- no membrane-bound organelles
- binary fission
SAME
- have DNA
- cytoplasm
- ribosomes
PROKARYOTIC
- DNA bound to protein
- linear DNA
- nucleus
- membrane-bound organelles
- mitosis and mesiosis
Prokaryotic cells divide by
binary fission
Compare and contrast the structure of plant and animal cells
PLANT
- cell wall
- chloroplasts
- definite shape
ANIMAL
- no cell wall
- lysosomes
- centiroles
Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the structure of cell membranes.
- Allows small substances like oxygen to pass through easily
- Allows cells to change shape easily
Functions of membrane protiens
- help cells communicate
- help cells maintain shape
- transport shared material
- help cells carry out changes made by chemical reactions
Define diffusion
Diffusion: the passive movement of anything from hight to low concentration
Explain the role of protein pumps and ATP in active transport around membranes
During active transport, protein pumps use ATP to move molecules in an area of high concentration to an area of low concentration
Explain passive transport across membranes through simple diffusion and facilitated diffusion.
Simple: movement of particles moves in directions of the concentration gradient
Facilitated: moved any way
Explain passive transport across membranes through simple and facilitated diffusion.
simple: in the direction of the concentration gradient
facilitated: in any direction
Explain how vesicles are used to transport materials within a cell between the rough ER, golgi apparatus and plasma membrane
Proteins are synthesized by ribosomes and enter the rER. Vesicles bud off from the rER and carry proteins to the Golgi.
The Golgi modifies proteins, and then the vesicles bud off from the Golgi and carry modified proteins to the plasma membrane.
Describe how the fluidity of the membrane allows it to change shape, break and reform during endocytosis and exocytosis
Phospholipids in the cell membrane are in fluid state, allowing the membrane to change its shape and also vesicles to fuse with it.
Discuss the implications of all cells being formed from pre-existing cells
There must have been a first cell that arose from non-living material billions of years ago.
The origins of all cells can be traced back through billions of years of evolution to “LUCA” the last universal common ancestor of all life on Earth.
Cells in our bodies originate from the first cell: the zygote produced by the fertilization of a sperm and egg.
Define spontaneous generation
The theory, now discredited, that living organisms can routinely emerge from nonliving matter independently of other living matter.
Why did bacteria grow in the broth of the flask that was left open by Pasteur?
Because be being exposed to CO2, bacteria was able to manifest in the broth
Explain why Pasteur’s experiment did not support spontaneous generation
Spontaneous generation did not occur in the flask not exposed to other elements (CO2)
Explain the historical thinking for spontaneous generation
Early philosophers and scientists were basing their ideas on what they could observe at the time.
Technological tools had not yet advanced to the point of being able to observe cells arising from other cells.
There was no reason to show that spontaneous generation wasn’t accurate. It’s hard to speak out against an idea when a majority support it.
Spontaneous generation was consistent with the other widely held cultural and religious beliefs of the time.
Define conformity bias and give a historical example
Conformity bias is the tendency to behave similarly to others in a group, against your own judgment. Conformity bias often stops creative or outside thinking. Historically conformity bias may have limited exploration into generation of living organism.
Define endosymbiotic theory
Mitochondria and chloroplasts were once other cells that were engulfed by other cells and formed a symbiotic relationship.
Evidence for the endosymbiotic theory
Mitochondria and chloroplasts have a double membrane and circular DNA
State the function of mitosis
The process of cells dividing and creating genetically identical “daughter” cells
list 4 processes that use mitosis
growth, repair, sexual reproduction, replacement
draw the typical eukaryotic cells as they would appear during the interphase and the 4 stages of miosis.
(//) -> (xx) -> (x-x) -> (//-//) -> (//)(//)
outline 4 events that occur during prophase
chromosome supercoil and become usable, centiroles move to opposite poles, mictrotubule spindles form between the centiroles, nucleous becomes invisible.
outline the process of metaphase, inclusive of the role of microtubules and the kinetochore
stage 2 spindle microtubules fully develop and attach to the centromere region but specifically the kinetochore.
outline process of anaphase
sister chromatids separate and are pulled towards opposite ends of cell. each is now its own chromosome
outline the events that occur during telophase
the chromosomes arrive at the cell poles and the miotic spindle disassembles
describe the structure of a replicated chromosome, including the centromere and sister chromatids
initally contains two identical DNA strands that are held together by the centromere -> X
explain why chromosomes must condense during mitosis
so it can be moved to the two sides of the cell more easily.
state the difference betweeen mitosis and cytokenesis
mitosis= division of the nucleus
cytokenesis= division of the cytoplasm both stages of the cell cycle
contrast cytokenesis in plants and animals
PC= cytokenesis occurs through the formation of a cell plate
AC= cytokenesis occurs through the formation of a cleavage furrow
list examples of metabolic reactions during interphase
protein synthesis
G1
cell growth
S
DNA synthesis
G2
cell worth
GO
miotic phase (mitosis and cytokenesis
tumor
mass of tissue caused by abnormal growth
benign
tumor that lacks the ability to invade other tissues and metastisize
malignant
tumor made of cells that can invade other tissues and metastisize
metasis
when cells from a malignant tumor spread from primary site
cancer
a disease caused by uncontrolled cell division of abnormal cells
mutagen
an agent that causes genetic mutation
ex: UV Radiation or chemicals
carcinogen
substance capable of causing cancer
describe why mutagens are not necessarily carcinogens
mutagens can change DNA structuree and carcinogens just affect uncontrolled cell division
describe how cancer arises
cells become cancerous after mutations accumulate in the genes that control the cell cycle
explain the relationships between oncogenes tumor suppressor genes and cancer
proto-onco genes are normal genes that code for proteins that help the cell move through the cell cycle, when proto-oncogenes are mutated, they become oncogenes that move the cell through the cell cycle even when it shouldn’t divide. there are tumor suppressor genes when cunvtion to stop a cell from dividing when it shouldn’t. tumor suppressors can mutate leading to the cell moving through the cycle when it shouldn’t. cancer develops when both types of genes are mutated and the cell divides without control.
state the formula for calculation of miotic index
number of cells undergoing miotic index
over
total number of cells
miotic index =
number of cells undergoing mitosis
—————————————-
total number of cells
expressed as a %
higher mitosis = growing faster
CANCER
tumors = uncontrolled cell division
mass of cells (tumor)
primary tumors
occur at the site of the original cancerous cells
metastasis
is the movement of those cells to other body regions
(secondary tumors)
mutagens
things that can cause mutations
carcinogens
mutagens that can cause cancer
- radiation
- viruses
- chemicals
oncongenes
genes that have the potential to cause cancer
