1.1 Introduction to cells Flashcards by Kaitlin Ellis

What are the three principles of cell theory?

All living things are composed of cells
The cell is the smallest unit of life

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What are the three exceptions to cell theory?

Striated muscle fibres
Aseptate fungal hyphae
Giant algae

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What theory does striated muscle fibres challenge?

That cells always function as autonomous units

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Why are striated muscle fibres an exception to cell theory?

They fuse to form very long fibres and have multiple nuclei

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What cell theory idea does aseptate fungal hyphae challenge?

That living structures are composed of discrete cells

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How are aseptate fungal hyphae an exception to cell theory?

They are not partitioned by septa and have a continuous cytoplasm

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What idea of cell theory does giant algae challenge?

That larger organisms are made up of many cells

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How does giant algae break cell theory?

Unicellular algae can grow up to 7cm in length

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What are the 7 functions of survival? Mr Sheng

Metabolism
Reproduction
Sensitivity
Homeostasis
Excretion
Nutrition
Growth

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What is metabolism?

Living things undertake essential chemical reactions

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What is reproduction?

Living things produce offspring either sexually or asexually

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What is sensitivity?

Living things are responsive to interval and external stimuli

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What is homeostasis?

Living things maintain a stable internal environment

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What is excretion?

Living things exhibit the removal of waste products

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What is nutrition?

Living things exchange materials and gases with the environment

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What is growth?

Living things can move and change shape or size

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How many life functions must unicellular organisms be able to carry out?

All of them

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How does paramecia do responsiveness?

They are surrounded by cilia which allow it to move

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How does paramecia do nutrition?

Engulfs food via a cytosome

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How does paramecium do metabolism?

Food particles are enclosed within small vacuoles that contain enzymes for digestion

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How does paramecium do excretion?

Solid wastes are removed by an anal pore whilst liquid wastes are pumped out by contractile vacuoles

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How does paramecium do homeostatsis?

Essential gases enter and exit the cell via diffusion

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How does paramecium do reproduction?

They divide assexually although horizontal gene transfer can occur via conjugation

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How does scenedesmus do nutrition/excretion?

They exchange gases and other essential materials via diffusion

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How does scenedesmus do metabolism?

Chlorophyll pigments allow organic molecules to be produced via photosynthesis

How does scenedesmus do reproduction?

Daughter cells form as non-motile autospores via the internal asexual division of the parent cell

How does scenedesmus do responsiveness?

They may exist as unicells or form colonies for protection

What do cells need to produce to survive?

Chemical energy

What does the production of chemical energy require?

The exchange of materials with the environment

What is the rate of metabolism of a cell?

A function of its mass/ volume

What do larger cells need more of to sustain essential functions?

Energy

What is the rate of material exchange a function of?

Its surface area

What does large membrane surface equate to more..?

Material movement

As a cell grows what increases faster?

Volume increases faster than surface area

What will happen if the metabolic rate exceeds the rate of exchange of vital materials and wastes?

The cell will eventually die due to to a low SA:Vol ratio

What does the increased volume and slower increase of surface area lead to?

Decreasing SA:Vol ratio

What do cells have to do in order to maintain a high SA:Vol ratio?

Divide and remain small

What type of cells and tissues will increase their surface area and why?

Cells and tissues specialised for gas/material exchange to optimise material transfer

What does the intestinal tissue of the digestive tract do to increase the surface area of the inner lining?

Form a ruffled structure

What do alveoli in the lungs have to increase the total membrane surface?

They have membranous extensions called microvilli

What is the formula for calculating magnification?

Magnification = image size / actual size M=I/A

How do you measure image size?

With a ruler

How do you measure actual size?

In accordance to the scale bar

What is the formula to calculate the actual size of a magnified specimen?

Actual size = Image size / magnification

What do light microscopes use to magnify images of mounted specimens?

Visible light and a combination of lenses

How can living specimens be viewed in light microscopes?

In their natural colour

When would a living specimen not be in their natural colour in a light microscope?

If a stain is applied to see specific structures

When drawing microscopic structures what three conventions should be followed?

Title of the specimen A magnification or scale Structures should be labelled

When do emergent properties arise?

When the interaction of individual component produce new functions

Why can multicellular organisms complete functions that unicellular organisms can not?

Due to the collective actions of individual cells combining to create new synergistic effects

What is the chain of organisation of multicellular organisms?

Cells Tissues Organ System Organism

What do cells grouped together form?

Tissues

What are organs formed of?

The functional grouping of multiple tissues

What will organs that interact form?

Organ systems capable of carrying out specific body functions

What do organ systems do?

Collectively carry out the life functions of the complete organism

What is differentiation?

The process during development where newly formed cells become more specialised and distinct form one another as they mature

What do all cells of an organism share?

An identical genome

What does each cell contain?

The entire set of genetic instructions for that organism

What will cause a cell to differentiate?

The activation of different genes within a given cell by chemical signals

What is packaged in the nucleus of a eukaryotic cell?

DNA with proteins to form chromatin

How are active genes usually packaged?

In an expanded form called euchromatin

How are inactive genes usually packaged?

In a condensed form called heterochromatin

Which type of gene packing is accessible to be transcribed?

Euchromatin

What will differentiated cells have different regions of?

DNA packaged as euchromatin and heterochromatin in accordance to their specific function

What does a cell lose when it differentiates and becomes specialied?

The capacity to form alternative cell types

What are the two key qualities of stem cells?

Self renewal and potency

What are stem cells?

Unspecialised cells with key qualities

What does self renewal mean?

They can continuously divide and replicate

What does potency mean?

They have the capacity to differentiate into specialised cell types

What are the four main types of stem cells?

Totipotent Pluripotent Multipotent Unipotent

What is a totipotent stem cell?

Can form any cell type as well as extra-embryonic tissue

What is pluripotent stem cells?

Can form any cell type

What is a multipotent stem cell?

They can differentiate into a number of closely related cell types

What is a unipotent stem cell

They can not differentiate but acn self renew

Why are stem cells necessary for embryonic development?

As they are an undifferentiated cell source from where all other cell types can be derived

What are considered to be non-stem cells?

Cell types that are not capable of self-renewal

Why have stem cells become a viable therapeutic option when tissues become damaged?

As non-stem cells cannot be regenerated or replaced

What can stem cells be used to do?

Replace damaged/diseased cells with health ones

What are the four thing using stem cell process require?

- surgical implantation into the tissue Suppression of host immune system to prevent rejection of cells Careful monitoring of new cells use of biochemical solutions to trigger stem cells into desired cell type

What is stargardts disease?

Inherited form of juvenile macular degeneration causing vision loss to the point of blindness

What is stargardts disease caused by?

A gene mutation that impairs energy transport in retinal photoreceptor cells

How is stargardts disease treated?

By replacing dead cells in the retina with functioning ones from stem cells

What is parkinsons disease?

A degenerative disorder of the central nervous system caused by the death of dopamine secreting cells in the midbrain

What do individuals with parkinsons typically exhibit?

Tremors, rigidity, postural instability and slowness of movement

How is parkinsons disease treated?

By replacing dead nerve cells with living dopamine producing ones

How are burn victims treated with stem cells?

Graft new skin cells to replace damaged tissue

How is type 1 diabetes treated with stem cells?

Replace non functioning islet cells with those capable of making insulin

How is paraplegia treated with stem cells?

Repair damage caused by spinal injuries to enable paralysed victims to regain movement

How is leukemia treated with stem cells?

Bone marrow transplants for those who are immunocompromised as a result of chemotherapy

What are the three sources stem cells can be derived from?

Embryos Umbilical cords/placenta Certain adult tissues

Whilst using multipotent adult tissue may be effective for certain conditions what is its limitations?

Its scope of application

What is the problem with stem cells derived from umbilical cord blood?

They need to be stored and preserved at a cost which raises issues of availability and access

What is the argument against using embryos?

It requires the destruction of a potential living organism

What are the two artificial stem cell techniques?

Somatic cell nuclear transfer and nuclear reprogamming

What is somatic cell nuclear transfer?

Involves the creation of embryonic clones by fusing a diploid nucleus with an enucleated egg cell

What is the problem with somatic cell nuclear transfer?

More embryos are created than needed which raises concerns about the exigency of excess embryos

What is nuclear reprogramming?

Induces a change in the gene expression profile of a cell in order to transform it into a different cell type

What are the disadvantages of nuclear reprogramming?

They is oncogenic retroviruses and transgenes which increases the risk of health consequences