Biology cue cards unit 1

MR SHENG

Metabolism

Reproduction

Sensitivity

Homeostasis

Excretion

Nutrition

Growth

Cell theory

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

Order of hierarchy (cells →)

Cells → Tissue → Organ → System → Organism

Where does a paramecium live

In aquatic habitats

What is special about the parameciums nucleus

Can divide to produce extra nuclei when cell reproduces

What is special about the parameciums food vacuoles

Contains smaller consumed organisms

Gradually digested

Nutrients absorbed into cytoplasm to provide energy and materials that are needed for growth

What is special about the parameciums cell membrane

Controls what enters/exits the cell

Excretion via diffusion through membrane

What is special about the parameciums Cytoplasm

where metabolic reactions occur

What is special about the parameciums cilia

Beating generates movement

Where are chlamydomonas found

In fresh water

What is special about the chlamydomonas nucleus

Divides to produce genetically identical nuclei for asexual reproduction

Can also fuse and divide for sexual reproduction

What is special about the chlamydomonas cytoplasm

Metabolic reactions take place here

What is special about the chlamydomonas contractile vacuoles

Fill up with water and expel it

Keeps cell water content within tolerable limits

What is special about the chlamydomonas flagella

Beating moves it through the water

What is special about the chlamydomonas eyespot

Cell senses where the most light is and moves towards it

What are emergent properties

Characteristics of the whole organism

Interaction of components of complex structures - cells do more together

What are atypical cells

Don’t conform to cell theory

3 examples of atypical cells

Striated skeletal muscle cells

Aseptate fungi

Giant algae

What is normal and different about Striated Skeletal muscle cells

Normal - surrounded by membrane from pre-existing cells

Different - Larger and longer, have > 1 nucleus, possibly several hundred

What is normal and different about Aseptate fungi

Normal - consists of thread-like structures called hyphae

Different - No Septa (division of hyphae), instead is 1 long tube like structure with many nuclei

What is normal and different about Giant Algae

Normal - unicellular

Different - Grow much larger but is still one cell

Why are cells so small

More efficient - quicker material exchange

Larger SA = more efficient

What is metabolic rate proportional to

Cell volume (larger the volume, more reactions take place)

Adaptions to small SA:V

Plants have a large central vaccole

Intestinal cells have villi and microvilli

Leaf palisade cells are column shaped

Elephants and foxes have large ears

Standard units

10^-3 of a metre = mm

10^-6 of a metre = micrometer um

10^-9 of a metre = nanometer nm

Common relative sizes

Molecules = 1nm

Membrane thickness = 10nm

Viruses = 100nm

Bacteria = 1 um

Organelle - up to 10 um

Cells up to 100 um

Magnification

Size of image/actual specimen size

Evolution of multicellular organisms

1) Grew as they were no longer limited by SA:V ratio

2) Cells could then specialise

3) Displayed emergent properties

What is a genome

Complete set of DNA instructions

Process of cell differentiation

* starts as zygote
* 4 divisions in 2-4 days
* Morula - 16 cell bundle
* 4-7 days becomes blastocyst
* Day 16 - gastrulation - 3 Germ layers form
* Embryo is foetus at 9 weeks
* Take from bone marrow

What is a totipotent cell called and what can it become

Zygote - any type of cell

What is a pluripotent cell called and what can it become

morula/blastocyst - every cell but placental

What can a multi-potent cell become

Specific to germ layer

What are the 3 germ layers

Endoderm - Internal organs

Ectoderm - Skin

Mesoderm - Blood cells

What is Stargarts disease due to

Recessive mutation of ABCA4

* causes membrane protein for active transport in retina to malfunction
* Photoreceptors then degenerate leading to blindness

How does stem cell therapy work for stargarts disease

Isolate human embryonic stem cells, transform them into RPE cells and transplant them into the eye, allowing sight to improve

What is leukaemia and what is it caused by

White blood cell cancer caused when leukocytes are produced in abnormally large numbers

How to treat leukaemia with stem cell therapy

1) Chemotherapy kills all bone marrow

2) donor bone marrow introduced into patient

3) stem cells migrate and produce healthy leukocytes

Characteristics of prokaryotes

* All bacteria are prokaryotes
* Has one long circular DNA chromosome
* Replicates via Binary Fission

Characteristics of eukaryotes

* Compartmentalised structure

How do Prokaryotes divide

Via binary fission

* Asexual
* Singular chromosome replicates and the copies move to opposite poles of the cell
* Cytoplasm divides afterwards
* Results in 2 genetically identical daughter cells

Advantages of being compartmentalised

* Enzymes and substrates can be much more concentrated
* Dangerous substances contained in an organelle
* Conditions (ph) can be maintained at ideal level
* Organelles and contents can move around the cell

Components and role of a nucleus

* double membraned with pores
* Contain chromosomes, DNA and histone proteins
* DNA replicated and transcribed to form mRNA

Components and role of the rough ER

* Made of Cisternae (flattened membrane sacs)
* 80S ribosomes attached
* Synthesises proteins for secretion out of cell


* Proteins pass into Cisternae and are carried in vesicles to Golgi apparatus

Components and role of the Golgi apparatus

Has cristernae with many nearby vesicles

Processes proteins bought in by vesicles

Then are packaged and go to plasma membrane for secretion

Components and role of lysosomes

Contains digestive enzymes

* breaks down ingested food in vesicles
* Breaks down organelles or even whole cell

Components and role of mitochondrion

* Double membraned
* Inner membrane forms cristae
* Fluid inside called matrix
* Produces ATP for aerobic cellular respiration

Components and role of ribosomes

80S in eukaryotes and not enclosed by membrane

Constructed in nucleolus in nucleus

Synthesises proteins

Components and role of chloroplasts

* Double membraned
* Thylakoids - flattened sacs of membrane forming grana
* Fluid filled space is the stoma
* Produces glucose via photosynthesis

Components and role of vacuoles and vesicles

* Single membraned encloses fluid
* Some food digested in vacuoles
* Contractile vacuoles experiment water
* Transport material in cell

Components and role of microtubules and centrioles

Fibres forming cellular matrix and holds organelles

* involved in chromosome movement and spindle fibre formation

Components and role of cilia and flagella

* Whip like structures projecting from cell
* Usually large and singular
* Cilia are smaller
* Used for locomotion

What does hydrophilic mean

Water loving

What does hydrophobic mean

Water hating

What does Amphipathic mean

Both water loving and hating properties

What did the 1920 Gorter and Grendel model deduce about the membrane

Membrane contained a bilayer

What did the 1930 Davson and Danielli model deduce about the membrane

Layers of protein are adjacent to the bilayer on both sides

What did the sandwich model explain

* how thin membranes are effective barriers to substance movement

What supported the idea of the sandwich model

1950’s high powered electron microscopes showing railroad track appearance

What is freeze-etched electron micrographs

* rapid freezing and then fracturing of the membrane


* Fractured along lines of weakness

What did the falsification of the sandwich model find

That proteins are varied in shape and size, not consistent with continuous layers

What is fluorescent antibody tagging

* Red or green fluorescent markers attached to antibodies binded to membrane proteins
* Some cells tagged red, others green, and are then fused together

What did antibody tagging illustrate about the bilayer

Proteins are free to move within the membrane and not fixed in an outer layer

Who created the fluid mosaic model and when

1966 or 1972 - Singer/Nicolson

Characteristics of phospholipids

* Amphipatic
* Made of
* Phosphate head
* 2 fatty acid tails

Structure of integral proteins

Hydrophobic on at least one surface part - are embedded

Transmembrane

Structure of peripheral proteins

Hydrophilic surface - not embedded

Have hydrocarbon chain attached - glycoprotein

Function of integral proteins

* immobilise enzymes for metabolic reactions
* Channels for passive transport and pumps for active transport

Structure of peripheral proteins

* Hormone binding sites and cell to cell communication
* Cell adhesion

Cholesterol location and role

* Embedded in fatty acid tails
* Maintains membrane fluidity

What is simple diffusion

Passive movement of particles from a region of high solute concentration to region of low solute concentration

What is the concentration gradient

Particles move from an area of high concentration to an area of low concentration

What is facilitated diffusion

* Large molecules/ions passing down a concentration gradient
* Through specific integral protein channel - changes shape
* NO ENERGY REQUIRED

Water potentials with more solute/less water

LOWER water potential

Water potentials with less solute/more water

HIGHER water potential

What is osmosis

Passive movement of water across the membrane down the concentration gradient

What is hypertonicity

Higher concentration of solutes to solution

What is hypotonicity

Lower concentration of solutes to solution

What is cytolysis

Cell swells and bursts as water rushes in

What is a flaccid cell

Cell loses shape as it loses water

What is active transport

movement of substances against the concentration gradient

Types of bulk transport

Endocytosis - into cell

* Phago - solids
* Pino - liquids

Exocytosis - out of cell

How does endocytosis occur

Membrane pulls inwards to form a pit

* becomes a vesicle and breaks off into the cytoplasm

How does exocytosis occur

* Vesicles fuse with membrane
* Contents expelled
* Membrane then flattens

What happens to proteins in the cell

* synthesised by ribosomes and enter rough ER
* Vesicles bud off and carry proteins to Golgi complex
* Modified by Golgi complex
* Vesicles bud off and carry proteins to membrane

How does active transport of sodium and potassium occur in axons

* 3 sodium ions enter pump and bind
* ATP transfers a phosphate group to pump, causing it to change shape
* 3 sodium ions released
* 2 potassium ions enter and bind
* Phosphate group released and pump changes shape
* 2 potassium ions released and sodium ions enter again

What is spontaneous generation

* formation of living organisms from non-living things

What was Louis Pasteurs experiment to disprove spontaneous generation

* Sterilise nutrient broth
* Place broth into 3 flasks
* Incubate broth/sample (1 in water, 1 sealed, 1 open)

How did Louis Pasteurs experiment prove spontaneous generation to be wrong

Formation of bacteria only in open flask

What experiment proved how cells first produced/formed carbon compounds/amino acids and how

* Stanley Milles and Harold Urey
* Passed steam through methane, hydrogen and ammonia mixture

Results in carbon compounds needed for life being produced
* Electrical discharges used to simulate lightning

How did carbon compounds first assemble into polymers in the first cells

* Deep sea vents
* Gushing hot water carrying reduced inorganic chemicals
* Readily accessible energy sources to assemble carbon compounds

How did membranes form in the first cells

* If phospholipids were present - form into bilayer
* Allows for different internal chemistry than surrounding area

How did the inheritance mechanism develop in the first cells

* Dna is mode of inheritance for living things
* Requires enzymes to replicate

Why could’ve RNA been an earlier mode of inheritance

* It can store genetic info
* Self-replicate
* Catalyse enzymes

What is endosymbiotic theory

Mitochondria were once free living prokaryote organisms

Larger organisms engulfed mitochondria, and unable to make their own energy, allowed mitochondria to continue living inside them

Evidence of endosymbiotic theory

* Has own genes on circular DNA - like prokaryotes
* Has own 70S ribosomes (typical of prokaryotes )
* Transcribes DNA and uses mRNA to synthesise proteins
* Only produced by division of more pre-exisiting cells

What is mitosis for

Growth and repair

What happens in the G1 phase of the cell cycle

Period of cell growth, duplication of organelle

What happens in the S phase of the cell cycle

DNA and chromosome replication

What happens in the G2 phase of the cell cycle

* Cell growth and preparation for mitosis