bio topic 1

3 parts of Cell theory

1. All cells come from pre-existing cells
2. Cells are the smallest unit of life
3. All living organisms are composed of cells

Life characteristics (MRS GREN)

Metabolism

Respiration

Sensitivity

Growth

Reproduction

Excretion

Nutrition

How many cells do unicellular organisms have?

1 cell that carry out all life functions

How many cells do multicellular organisms have?

They are composed of more than 1 cell. They can be a part of a tissue, multiple cells, etc.

What do unicellular and multicellular cells have in common?

DNA, Cytoplasm, Plasma/Cell membrane, ATP/energy production, ribosomes

When cells group together what do they form?

Tissues

Who was the first person to see bacterial cells?

Anton Van Leeuwenhoek

What did Anton Van Leeuwenhoek call cells?

Animalcules

Who used cells first?

Robert Hooke

Who first suggested cell theory

Theodor Schwann

What living organisms should carry out life functions?

Paramecium, animal, plants, fungi, proteins, etc

Characteristics of cells

* Microscopic,
* Cell membrane
* Genetic information
* have energy release systems

3 exceptions to cell theory

* Striated Muscle fibre
* Giant algae
* aseptate fungal hyphae

Characteristics of striated muscle fibres

* Long multinucleated fibres despite being surrounded by 1 continous membrane
* Challenges the idea that cells always function as autonomous units

Characteristics of Aseptate fungal hyphae

* No internal walls (septa)
* Continious cytoplasm along hyphae
* challenges the idea that living things are made of discrete cells

Characteristics of giant algae

* large size (> 7mm)
* challenges the idea that bigger organisms are made of many microscopic cells

examples of unicellular organisms

paramecium, algae eg. chlorella

How do paramecium reproduce?

Asexual reproduction by binary fission

Draw a paramecium and label the life functions

Draw a algae eg. chlorella and label the life functions

Does volume increase faster or slower than SA

Volume

Rate of metabolism formula

Mass/volume

Do cells need to maintain a high or low SA:V ratio to survive

high

What happens if metabolic rate exceeds the rate of exchange of materials and wastes?

low SA:V ratio, cell will die

How do organisms maximise their SA:V ratio? (3 ways)

1. cell growth and divide
2. cells compartmentalise (organelles in eukaryotes)
3. Some organisms fold to maximise SA:V eg. small intestine, brain, mitochondria, etc

Draw a mitochondria and describe the function

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Magnification formula

Size of image/actual size

1cm = how many mm

10 mm

1mm = how many micrometer μm

1000μm

1μm = how many nanometer

1000 nm

Why do multicellular ocells display emergent properties and cell differentiation occur?

Every cell contains a copy of each gene but only certain genes are turned on

What are emergent properties

The whole organism can do more than individual cells

Why can multicellular organisms complete functions that unicellular cells can't?

Because cells may group together to form tissues -> organs -> organ systems -> carry out body functions -> organs tgt carry out life functions of complete organisms

Multicellular cell special cases

* Volvox aureus
* c

Draw and describe volvox aureus

Draw and describe c.elegans

Differentiation

Newly formed cells become more specialised and distinct from each other as they mature

If each cell of an organism share an identical genome, how do cells differentiate?

* Each cell has an entire set of genetic instructions for that organism
* Activation of different introductions (genes in a cell by chemical signals -> differentiate)

Gene packaging

* the nucleus of eukaryotic cell has DNA that is packaged to form chromatin

How are active genes packaged?

Active genes are usually packaged in the form of euchromatin (the area of the chromosome which is rich in genes that actively participate in the transcription process.)

How are inactive genes packaged?

Inactive genes are usually packaged in the form of heterochromatin ( dense material that is typically found at centromeres and telomeres. It mostly consists of repetitive DNA sequences and non-coding RNA transcripts and is relatively gene poor. Its most notable property is its ability to silence euchromatic) gene expression.)

Characteristics of stem cells

* unspecialised
* Self-renewal (continously divide and replicates)
* Potency (ability to differentiate into specialised cell types)

Therapeutic uses of stem cells

* **regenerate tissue**
* **grow organs**
* **cure diseases caused by loss of cell function**
* **leukemia, Stargardts disease**

non-therapeutic uses of stem cells

growing meat in a lab

Totipotent

Any cell type including placental tissue and zygote

Pluripotent

Any (embryonic stem cells)

Multipotent

Differentiate into a number of closely-related cell types eg. bone marrow (Adult stem cells)

Unipotent

Cannot differentiate but can self renew eg. muscle stem cells

State the property of stem cells that makes them useful in medical treatment.

The ability to differentiate into specialised tissue, replace damaged/diseased cells with healthy functioning ones

Explain how multicellular organisms develop specialised tissues.

Only some genes are expressed in each cell type/tissue, so they become differentiated

Outline one therapeutic use of stem cells

* they can divide and differentiate to all types of cells (pluripotent/totipotent)
* Replace diseased/dysfunctional cells with healthy ones
* dangers of rejection of cells so we need to suppress immune systems by using drugs
* implant cells into patient's tissues so they can function with body's natural cells

Stem cell therapy examples (therapeutic)

* Stargardt’s disease
* parkinson’s disease
* leukemia
* paraplegia
* diabetes
* burn victims (new skin cells to replace damaged tissue)

Stargardt's disease

* Inherited
* Juvenile macular degeneration that causes progressive vision loss to blindness
* caused by gene mutation that impairs retinal photoreceptor cells -> cause degeneration
* Replace dead cells with functioning ones from stem cells

Parkinson's disease

* Degenerative disorder of the central nervous system caused by the death of dopamine secreting cells in the midbrain
* Exhibit tremors, rigidity, slow movement, postural inability
* replace dead nerve cells with living, dopamine-providing ones

Where are stem cells derived from?

Embryos, umbilical cord blood, placenta, adult tissues like bone marrow (not pluripotent cells)

What are the ethical considerations of using stem cells?

Multipotent : only effective for certain conditions

Umbillical cord blood needs storage at $$$ and not avaliable everywhere

embryos has the highest yield of pluripotent stem cells but require the destruction of potential living organism

1st compound microscope by ? (when)

Zacharias Janssen 1590

Who first used light microscope? and when?

1dst used light microscope to look at thin slices of plant tissue, coined the term "cell": Robert hooke 1665

who first saw microscopic organisms?

1st to see microscopic organisms (in pond H20) called animalcules: Anton Van Leeuwenhoek 1673

Who was responsible for each of the cell theory?

"All living things are made of cells": Mathias Schleiden 1838

"All living things are made of cells": Theodore Schwann 1839

All cells come from pre-existing cells: Rudolph Virehow

are electron or light microscopes more magnified?

Electrons

Venn diagram comparing prokaryotes and eukaryotes

Draw a prokaryotic cell and label life functions

Draw and explain steps of binary fission

Label and explain prokaryotic features

Cytoplasm: Fluid component of the cell

Nucleoid: region of DNA (circular)

Plasmids: CIrcular DNA transferred between bacteria

Bacteria acquire genetic material through horizontal gene transfer

Ribosomes: 70s, RNA and protein responsible for polypeptide synthesis

Cell membrane: Semi permeable, selective barrier

Cell wall: Rigid, maintains shape and prevent bursting

Slime capsule: thick polysaccharide layer to protect against drying out (dessication) and phagocytosis

Flagella: Contain motor protein that enables movement

Pili: enable adherence to surfaces (attachment pili) or mediate bacterial conjugation (sex pili)

How did eukaryotic cells evolce from prokaryotes?

Endosymbiosis

4 eukaryotic kingdoms

* Protista: Unicellular/multicellular organism without specialised tissue
* Fungi: Have cell wall made of chitin and obtain nutrition via heterotrophic absorption
* Plantae: Have cell wall made of cellulose and obtain nutrition autotrophically (photosynthesis)
* Animalia: No cell wall and obtain nutrition via heterotrophic ingestion

Draw an animal cell

Draw a plant cell

What are the organelles in eukaryotes (animal and plant cells) and explain their function?

* Nucleus: Double membrane with pores, contains nucleolus, stores DNA (genetic material) as chromatin, site of ribosome assembly

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* Endoplasmic reticulum: R or S, transports materials between organelles. SER: LIPIDS, RER: PROTEINS

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* Golgi apparatus: Assembly of vesicles, involved in sorting and storing and modification and export of secretory products

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* Mitochondrion: Double membrane, inner membrane folded into internal cristae, site of aerobic respiration and atp production

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* Centrosome: Microtubule organising centre, contains centrioles in animal cells not plant cells, radiate microtubules from spindle fibres, contribute to cell division (mitosis/meiosis)

Organelles in prokaryote and eukaryotes:

* Ribosome:

2 subunits made of RNA and protein, 80s eukaryotes, 70s prokaryotes, site of protein synthesis (eg. in translation)

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* Cytoskeleton:

Filamentous scaffolding in the cytoplasm, the fluid portion of the cytoplasm is called the cytosol. It provides internal structure and mediates intracellular transport, less developed in prokaryotes

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* Plasma membrane:

Phospholipid bilayer embedded with proteins, not an organelle but an important structure, semi-permeable and selective

organelles in plant cells only

Chloroplast:

Double membrane with internal stacks of membranous discs

Site of photosynthesis

molecules are stored. inplastids

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Vacuole:

Large and central

fluid-filled

surrounded by a membrane

Maintains hydrostatic pressure

Animal cells may have small temporary vacuoles

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Cell wall:

External layer made of cellulose

not really an organelle

provides support and prevent excess water uptake

Organelles in animal cells only

Lysosome: Membranous sacs filled with hydrolytic enzymes

breakdown/hydrolysis of macromolecules

Compare organelles in plant and animal cells

What does the fluidity of the phospholipid bilayer allow

spontaneous breaking and reforming of membranes (endocytosis and exocytosis)

Hydrophilic

Water loving

Hydrophobic

water hating

What is the hydrophilic head composed of

Polar, composed of glycerol and phosphate molecule

what are hydrophobic tails compsed of

fatty acid hydrocarbon chains

Draw phospholipid bilayer membrane

**Functions of proteins in phospholipid bilayer: JET RAR**

**Joining 2 cells together**

**Enzymes fix membranes and localises metabolic pathways**

**Transport: Facilitated diffusion and active transport**

**Recognising cells**

**Attachment points for the cytoskeleton and extracellular matrix**

**Receptors for peptide hormones**

Functions of cholesterol

* **Maintain integrity and stability, reduce fludity**
* **Amphipathic (hydrophilic and hydrophobic)**
* **Separate phospholipid tails to prevent crystalisation of membrane**
* **secure peripheral proteins**
* **reduce fluidity**
* At high temperatures it stabilises the membrane andn raises the melting point

At low temperatures it gets between the phospholipids and prevents clustering

Draw and label the davson danielli model. State the assumptions and falsification.

how does unsaturated hydrocarbon tails influence membrane fluidity

increase fluidity as they are less viscous and more susceptible to changes in kinetic energy. Because lipid chains with double bonds (unsat fatty acids) have kinked hydrocarbon tails that are harder to pack together

2 cell membrane characteristics

Semi permeable

selective

Semi-permeable

large and charges substances are typically blocked

Selective

Regulate the passage of materials that cannot freely cross

Passive transport

Movement of materials along/down a conc. gradient

Substances are typically blocked

Doesn't require ATP (ATP hydrolysis)

Types of passive transport

Simple diffusion

osmosis

Facilitated diffusion

Osmolarity

The measure of solute conc. defined by the no. of osmoles of a solute per liter of solution (osmol/L)

Simple diffusion

passive movement of small/lipophillic/non-polar molecules until they become evenly dispersed (equilibrium)

No need proteins

The rate of diffusion can be influenced by temperature (affect the kinetic energy of particles), molecular size(larger molecules are subjected to greater resistance) and the steepness of the gradient.(rate of diffusion increase with high conc. gradient) .

eg. O2, CO2, glycerol

Osmosis

net movement of water molecules across the semipermeable membrane from low solute conc to high until equilibrium

dependent on solute conc.

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Water

Universal solvent, dissolve polar/charged molecules

Can Solutes cross the cell membrane unaided

No

Facilitated diffusion

Passive movement of large/charged/polar molecules across the cell membrane with the help of membrane proteins

Carrier and channel mediated

eg. ions, sucrose

how does Active transport move materials, against or along a conc. gradient

Movement of materials AGAINST a conc. gradient using energy

Low conc to high conc

What energy do we use in active transport?

need to use energy eg. generated by:

* Primary active transport (direct): hydrolysis of ATP to mediate transport
* pump-mediated: specific solute will bind to protein pump inside the membrane, hydrolysis of ATP to ADP + Pi will make a conformational change in the protein pump and the solute molecule will move across the membrane against the gradient and the molecule will be released

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* Secondary active transport: Indirect coupling with another molecule, moving along conc. gradient
* carrier mediated

Hypertonic

High sol. conc and osmolarity

GAIN H20

Hypotonic

Low sol conc. and osmolarity

LOSE H20

Isotonic

Sol with same osmolarity

SAME solute conc, NO net water flow