Topic 1.1: Introduction to Cells Flashcards
What are the 3 principles of cell theory?
The cell theory states that:
- All living things are composed of cells (or cell products)
- The cell is the smallest unit of life
- Cells only arise from pre-existing cells
What are the 7 basic functions integral to survival?
metabolism, reproduction, sensitivity, homeostasis, excretion, nutrition, and growth
Define metabolism (in terms of basic functions needed for survival)
Living things undertake essential chemical reactions
Define reproduction (in terms of basic functions needed for survival)
Living things produce offspring, either sexually or asexually
Define sensitivity (in terms of basic functions needed for survival)
Living things are responsive to internal and external stimuli
Define homeostasis (in terms of basic functions needed for survival)
Living things maintain a stable internal environment
Define excretion (in terms of basic functions needed for survival)
Living things exhibit the removal of waste products
Define nutrition (in terms of basic functions needed for survival)
Living things exchange materials and gases with the environment
Define growth (in terms of basic functions needed for survival)
Living things can move and change shape or size
Which of the 7 basic functions integral to survival is: Living things undertake essential chemical reactions?
metabolism
Which of the 7 basic functions integral to survival is: Living things produce offspring, either sexually or asexually?
reproduction
Which of the 7 basic functions integral to survival is: Living things are responsive to internal and external stimuli?
sensitivity
Which of the 7 basic functions integral to survival is: Living things maintain a stable internal environment?
homeostasis
Which of the 7 basic functions integral to survival is: Living things exhibit the removal of waste products?
excretion
Which of the 7 basic functions integral to survival is: Living things exchange materials and gases with the environment?
nutrition
Which of the 7 basic functions integral to survival is: Living things can move and change shape or size?
growth
How do you calculate magnification of a drawing or image?
Magnification = Image size (with ruler) ÷ Actual size (according to scale bar)
How do you calculate the actual size of a drawing or image?
Actual Size = Image size (with ruler) ÷ Magnification
How do light microscopes work?
Light microscopes use visible light and a combination of lenses to magnify images of mounted specimens
What type of microscope uses visible light and a combination of lenses to magnify images of mounted specimens?
light microscopes
What is the organisation of multicellular organisms?
Cells may be grouped together to form tissues
Organs are then formed from the functional grouping of multiple tissues
Organs that interact may form organ systems capable of carrying out specific body functions
Organ systems collectively carry out the life functions of the complete organism
Define cell differentiation
Differentiation is the process during development whereby newly formed cells become more specialised and distinct from one another as they mature
What is the process during development whereby newly formed cells become more specialised and distinct from one another as they mature?
differentiation
What causes differentiation?
The activation of different instructions (genes) within a given cell by chemical signals will cause it to differentiate
How are active genes packaged within the nucleus?
Active genes are usually packaged in an expanded form called euchromatin that is accessible to transcriptional machinery
How are inactive genes packaged within the nucleus?
Inactive genes are typically packaged in a more condensed form called heterochromatin (saves space, not transcribed)
Define euchromatin
type of chromatin that form when active genes are packed together
Define heterochromatin
type of chromatin that form when inactive genes are packed together
What are the two qualities of unspecilised cells?
self renewal and potency
Define self renewal (in terms of unspecialised cells)
They can continuously divide and replicate
Define potency (in terms of unspecialised cells)
They have the capacity to differentiate into specialised cell types
Define stem cells
unspecialised cells
What is unspecialised cells’ quality to continuously divide and replicate called?
self renewal
What is unspecialised cells’ quality to differentiate into specialised cell types called?
potency
What are the four main types of stem cells present at various stages of human development?
totipotent, pluripotent, multipotent, and unipotent
What can a totipotent stem cell form?
Can form any cell type, as well as extra-embryonic (placental) tissue (e.g. zygote)
What can a pluripotent stem cell form?
Can form any cell type (e.g. embryonic stem cells)
What can a multipotent stem cell form?
Can differentiate into a number of closely related cell types (e.g. haematopoeitic adult stem cells)
What can a unipotent stem cell form?
Can not differentiate, but are capable of self renewal (e.g. progenitor cells, muscle stem cells)
What type of stem cell Can form any cell type, as well as extra-embryonic (placental) tissue (e.g. zygote)?
totipotent stem cell
What type of stem cell Can form any cell type (e.g. embryonic stem cells)?
pluripotent stem cell
What type of stem cell Can differentiate into a number of closely related cell types (e.g. haematopoeitic adult stem cells)?
multipotent stem cell
What type of stem cell Can not differentiate, but are capable of self renewal (e.g. progenitor cells, muscle stem cells)?
unipotent stem cell
What are the four steps that are required for stem cells to replace damaged or diseased cells with healthy ones?
The use of biochemical solutions to trigger the differentiation of stem cells into the desired cell type
Surgical implantation of cells into the patient’s own tissue
Suppression of host immune system to prevent rejection of cells (if stem cells are from foreign source)
Careful monitoring of new cells to ensure they do not become cancerous
What is the first step that is required for stem cells to replace damaged or diseased cells with healthy ones?
The use of biochemical solutions to trigger the differentiation of stem cells into the desired cell type
After The use of biochemical solutions to trigger the differentiation of stem cells into the desired cell type What is the next step that is required for stem cells to replace damaged or diseased cells with healthy ones?
Surgical implantation of cells into the patient’s own tissue
After Surgical implantation of cells into the patient’s own tissue What is the next step that is required for stem cells to replace damaged or diseased cells with healthy ones?
Suppression of host immune system to prevent rejection of cells (if stem cells are from foreign source)
After Suppression of host immune system to prevent rejection of cells (if stem cells are from foreign source) What is the next step that is required for stem cells to replace damaged or diseased cells with healthy ones?
Careful monitoring of new cells to ensure they do not become cancerous
What is Stargardt’s disease?
An inherited form of juvenile macular degeneration that causes progressive vision loss to the point of blindness
What causes Stargardt’s disease?
Caused by a gene mutation that impairs energy transport in retinal photoreceptor cells, causing them to degenerate
How is Stargardt’s disease treated?
Treated by replacing dead cells in the retina with functioning ones derived from stem cells
What is Parkinson’s disease?
A degenerative disorder of the central nervous system caused by the death of dopamine-secreting cells in the midbrain
What are some symptoms of people with Parkinson’s disease?
individuals with Parkinson’s disease typically exhibit tremors, rigidity, slowness of movement and postural instability
How is Parkinson’s disease treated?
Treated by replacing dead nerve cells with living, dopamine-producing ones
How is leukemia treated using stem cells?
Bone marrow transplants for cancer patients who are immunocompromised as a result of chemotherapy
How is paraplegia treated using stem cells?
Repair damage caused by spinal injuries to enable paralysed victims to regain movement
How is diabetes treated using stem cells?
Replace non-functioning islet cells with those capable of producing insulin in type I diabetics
How are burn victims treated using stem cells?
Graft new skin cells to replace damaged tissue
What are the 3 sources where stem cells can be derived from?
Embryos (may be specially created by therapeutic cloning)
Umbilical cord blood or placenta of a new-born baby
Certain adult tissues like the bone marrow (cells are not pluripotent)
What is an ethical consideration associated with the use of stem cells from adult tissues?
Using multipotent adult tissue may be effective for certain conditions, but is limited in its scope of application
What is an ethical consideration associated with the use of stem cells from umbilical cord blood or placenta?
Stem cells derived from umbilical cord blood need to be stored and preserved at cost, raising issues of availability and access
What is an ethical consideration associated with the use of stem cells from embryos?
The greatest yield of pluripotent stem cells comes from embryos, but requires the destruction of a potential living organism
What are two artificial stem cell generating techniques?
Somatic cell nuclear transfer (SCNT) and Nuclear reprogramming
What is somatic cell nuclear transfer (SCNT)?
Involves the creation of embryonic clones by fusing a diploid nucleus with an enucleated egg cell (therapeutic cloning)
What is Nuclear reprogramming?
Induce a change in the gene expression profile of a cell in order to transform it into a different cell type (transdifferentiation)
What is a disadvantage of somatic cell nuclear transfer?
More embryos are created by this process than needed, raising ethical concerns about the exigency of excess embryos
What is a disadvantage of Nuclear reprogramming?
Involves the use of oncogenic retroviruses and transgenes, increasing the risk of health consequences (i.e. cancer)
What Involves the creation of embryonic clones by fusing a diploid nucleus with an enucleated egg cell (therapeutic cloning)?
somatic cell nuclear transfer (SCNT)
What involves Induce a change in the gene expression profile of a cell in order to transform it into a different cell type (transdifferentiation)?
Nuclear reprogramming
The rate of metabolism of a cell is a function of its
mass / volume (larger cells need more energy to sustain essential functions)
The rate of material exchange is a function of its
surface area (large membrane surface equates to more material movement)
Explain surface area to volume ratio
As a cell grows, volume (units3) increases faster than surface area (units2), leading to a decreased SA:Vol ratio
If metabolic rate exceeds the rate of exchange of vital materials and wastes (low SA:Vol ratio), the cell will eventually die
Hence growing cells tend to divide and remain small in order to maintain a high SA:Vol ratio suitable for survival
What is the relative size of eukaryotic cell (plant)?
Eukaryotic cell (plant) = ~100 μm
What is the relative size of eukaryotic cell (animal)?
Eukaryotic cell (animal) = ~10 – 50 μm
What is the relative size of organelle?
Organelle (e.g. mitochondrion) = ~1 – 10 μm
What is the relative size of prokaryotic cell (bacteria)?
Prokaryotic cell (bacteria) = ~1 – 5 μm
What is the relative size of virus?
Virus = ~100 nm
What is the relative size of plasma membrane?
Plasma membrane = ~7.5 nm
What is the relative size of molecules?
Molecules (e.g. glucose) = ~1 nm
What is the relative size of atoms?
Atoms = ~100 pm
