IB BIO TOPIC 2.1 : CELLS Flashcards
What organisms are considered acellular ?
Unicellular organisms
Viruses
What are the 4 outlines of cell theory ?
- ) living organisms are composed of cells
- ) Cells are the smallest unit of life
- ) Cells come from pre-existing cells
- ) Cells are units if structure and function
What makes a hypothesis become a theory ?
Accumulation if evidence
A theory can be : … Or ….
Rejected or adapted
As evidence is accumulated theories need to be :
Reviewed or altered or abandoned
Outline 3 characteristics of the cells :
- )nothing smaller than a cell can survive independently
- ) sub cellular structures cannot live independently (nuclei, Golgi, chloroplast…)
- ) the lower limit on cell size is about 200nm
Outline 4 points on “origin of life”
- ) life always existed is incompatible with geological evidence on age of earth
- ) exception made for origin of life, cells must have arisen from non living substances
- ) condition of early earth are Anaerobic = precluding the formation of cells from non-living substances
State the advantages of Light Microscope
- ) colour images instead of monochromic
- ) easily prepared sample material
- ) possibility to observe living material and movement
- ) larger field of view
State the advantages of Electron Microscopes
- ) higher resolution
- ) more separate particles and clearer picture
- ) Higher magnification to see smaller objects
State the 6 functions of life carried by unicellular organisms :
Metabolism Sensitivity Homeostasis Growth Reproduction Nutrition
Explain Metabolism
Chemical reactions inside the cells , including cell respiration to release energy.
Explain sensitivity
Perceiving and responding to changes in the environment
Explain homeostasis
Keeping conditions inside the organisms within tolerable limits
Explain growth
An irreversible increase in size
Explain reproduction
Producing offspring either sexually or asexually
Explain nutrition
Obtaining Food to provide energy and all the material needed for growth
State the sizes of the following : Molecules Cell membrane Viruses Bacteria Organelles Eukaryotic cells
Molecules : ~1nm Cell membrane : ~ 10nm Viruses : ~ 100nm Bacteria :~ 1um Organelles : up to 10um Eukaryotic cells : up to 100um
What does “um” and “nm “mean ?
And what are their sizes in relation to each other ?
"nm" = nanometer "um" = micrometer
1000nm = 1um 1000um = 1mm
State the sizes of these : Atom Small molecules Lipids Proteins Ribosomes Mitochondrion
Atoms = ~0.1 nm Small molecules =~ less than 1nm Lipids =~ 1-5 nm Proteins =~ 5-10 nm Ribosomes =~ less than 50 nm Mitochondrion =~ 2um
What is the size of most plant and animal cells ?
Between 100um to 10 um
What is the magnification formula ?
Size of image / actual size of specimen
What is surface area to volume ratio in a cell ?
Surface area to volume ratio decreases when VOLUME INCREASES.
Larger the object = smaller the surface area to volume ratio = slower diffusion rate
State 1 characteristic of a unicellular organism :
Must solve all of life’s challenges within the confines of a single cell
State 4 characteristics of Multicellular organisms :
- ) can differentiate into a variety of interdependent cell types
- ) each specialised to carry out a subset of functions
- ) thereby achieving a greater efficiency
- ) through division of labor among a multicellular cooperative
What is cellular differentiation ?
The development of cells in specific ways
Ex. Hormones, cell to cell signals, and chemicals determines how a cell develops
Why do cells in multicellular organism differentiate ?
To become specialised !
For how many functions is each cell specialised ?
Only one.
Ex. Nerve cells transmit messages
What do groups of differentiated cells form ?
A tissue
What do cells contain ?
Nucleus (chromosomes—>DNA—-> Genes)
What is a tissue ?
A tissue is an integrated group of cells that have a common structure and function
Do cells have the possibility to carry any specialisation ?
Yes. Cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.
What is an organ ?
An organ is a centre of body function specialised for that one function that is composed of several different types of tissue
What is an organ system ?
An organ system is a group of organs that specialise in a certain function together
What do stem cells do ?
They retain the capacity to divide and have the ability to differentiate along different pathways.
Outline the 4 therapeutic use of stem cells
- ) Bone marrow transplants use hematopoietic stem cells(HScells)
- ) HS cells are found in bone marrow and divide continually (producing red and white blood cells)
- ) Just 100 HS cells can replace the blood system of mice when bone marrow is destroyed by radiation
- ) HS cells are used in the treatment of numerous blood disorders.
Name 4 blood disorders than can be cured by HS cells
- ) Acute leukemia
- ) SCID (severe combined immune deficiency)
- ) Multiple myeloma
- ) lymphoma
Explain the 5 steps of lymphoma
- ) cells are removed from the bone marrow of the patient
- ) High doses of chemotherapy are taken by the patient to kill dividing cells in the body
- ) Both cancerous and normal cells are killed
- ) HS cells from the bone marrow are then transplanted back into the patient
- ) These HS cells then fully restore healthy production of blood cells in the bone marrow.
What are the ethical issues of embryonic stem cells?
Using embryonic stem cells involves the death of an early stage embryos.
What are the ethical issues regarding therapeutic cloning ?
Therapeutic cloning could reduce suffering for the patients with wide variety of conditions.
Define an organelle
An organelle is a discrete structure within a cell that has a specific function, it also needs to be covered by its own membrane.
Why is the surface are to volume ration significant as a factor limiting cell size ?
The rate of heat production/waste production/resource consumption of a cell is a function of its volume, whereas the rate of exchange of materials and energy (heat) is a function of its surface area.
What are emergent properties ?
Emergent properties arise from the interaction of component parts: the whole is greater than the sum of its parts.
ex. Life
