Lecture 1,2&3- Cells, the basis of life

Why must allometry occur

Why must allometry occur

An organisms' volume will increase quickly but surface area will not match this and therefore an adaptation must occur

Why is comparative physiology important

Allows researchers to question the origins of life, evolution of different body plans and how biological adaptations have arisen.

Why do we use logs

• Allow us to make larger numbers into a more manageable scale

• Allow the relationship between two variables to be distinguished

• Find the cause of an effect

Why are cells around the same size

Size is a limiting factor and increasing size means increasing complexity

Where is DNA is prokaryotic & eukaryotic cells

Prokaryotic: a non-membrane enclosed region called the nucleoid

Eukaryotic: the nucleus

Where are microtubules found

All eukaryotic cells

Where are microfilaments found

all eukaryotic cells

Where are intermediate filament cells found

In cells of some animals

Where are free ribosomes found?

suspended in the cytosol

Where are bound ribosomes found?

Outside of the ER or nuclear envelope

Which type of cells are larger

Eukaryotic

What structures carry DNA

Chromosomes

What is transmission electron microscope used for

study the internal structure of cells

What is the pore complex of the nucleus?

The protein structure that lines the pore and regulates entry and exit of particles

What is the nuclear matrix

Framework of protein fibers extending throughout the nuclear interior.

What is the nuclear lamina

Net like array of protein filament that maintains the shape of a nucleus by supporting nuclear envelope

What is the nuclear envelope?

double membrane of lipid bilayers with associated proteins that surrounds the nucleus

What is the maximum size a light microscope can go to

0.2 micrometers

What makes up the cytoskeleton

microtubules, microfilaments, intermediate filaments

What is needed for adaptations

Divergence

What is isometry

When something 1s scaled up or down in order to carry out the same function

What is chromatin

The complex of DNA and proteins which make up chromosomes

What is body Mass

The quantity of matter in a given volume of body

What is atomic force microscopy used for

Atomic scale

What is allometry

When there is a change/ variation needed in order for something to carry out the same function

Disadvantage of the electron microscope

the method used to prepare the specimen will kill the cells so that living cells cannot be observed and artifacts may be introduced

What structures help to organise genetic material so it functions efficiently

Nuclear lamina and matrix

What happens with increasing size

The area over which exchange happens becomes proportionally smaller in relation to the mass of the organism it supplies

What happens to surface area as a cell's size increases

It grows proportionally less than its volume so a smaller cell has a greater ratio of SA to volume

What two features do cells share

• Surrounded by a plasma membrane

• Have a cytosol where subcellular components are suspended

What does the ER consist of

network of membranous tubules and sacs called cisternae

What does microscopy do

Looks at things at a microscopic level

What is required for cell motility

interaction of the cytoskeleton with motor proteins

Important parameters in microscopy

1. Magnification- ratio of image size to real size

2. Resolution- measure of the clarity of the image

3. Contrast- difference in brightness between the light and dark sections of the image

What are vacuoles?

large vesicles derived from the ER and Golgi apparatus

How are food vacuoles formed

phagocytosis

What are contractile vacuoles

found in many freshwater protists, pump excess water out of cells

Uses from comparing biological adaptations

Antibiotics, solar cells

The decrease in the SA / volume makes it necessary for what transport systems

• Obtaining food

• Gas exchange

• Transport across the body

What is the cortex

Outer cytoplasmic layer of a cell which has a gel like consistency

The basic fabric for most biological membranes

Double layer of phospholipids and other lipids with diverse proteins embedded

Function of Rough ER

protein synthesis

Role of plasma membrane

Selective barrier which controls what enters and exits the cell allowing enough nutrients and oxygen to service the cell

Nucleolus

Mass of densely stained granules and fibres adjoining part of the chromatin

Myosin

The protein which makes up the thick filaments of muscle fibres which interact to cause muscle contraction

Multinucleic

Cell that has more than one nucleus

Microvilli

projections that increase the cell's surface area

Microtubule structure

Hollow tubes made of tubulin (a dimer consisting of alpha and beta tubulin)

Microtubule size

25nm with 15nm lumen

Microtubule function

maintenance of cell shape, cell motility, chromosome movements in cell division, organelle movements

Microfilament structure

two intertwined strands of actin

Microfilament size

7 nm

Micro filament function

Maintain cell shape, changes in cell shape, muscle contraction, cytoplasmic streaming in plants, cell motility & cell division

Metabolic rate and mass relationship

Rate = 70 x mass ^ 3/4

Lysosomes

Membrane bound organelle containing digestive enzymes

Function of lysosomes

Contains hydrolytic enzymes to digest macromolecules

Intermediate filaments structure

fibrous proteins coiled into cables

Size of intermediate filaments

8-12nm

Function of intermediate filaments

maintain cell structure and anchorage of nucleus and certain other organelles

How does electron microscopy work

Uses electrons which are scattered onto a sample

How do proteins leave the ER

The ER membrane keeps secretory proteins separate from cytosol proteins and the secretory proteins are wrapped up in the membranes of vesicles which bud off from the ER

How do light microscopes work?

visible light passes through a specimen and then through glass lenses, which magnify the image

function of Golgi apparatus

Modify, sorts and packages proteins and other materials from the ER for storage in the cell or secretion outside the cell

What is the Golgi apparatus

System of flat membranous sacs called cisternae that modify & package proteins & lipids for export by the cell

Glycoproteins

A protein with one or more covalently attached carbohydrates.

Cytoskeleton function

• Mechanical support to cell

• Maintain cell shape

• Provide anchorage for organelles

• Involved in some types of cell motility

Smooth ER function

• synthesis of lipids and membrane phospholipids

• Synthesis of steroid hormones

• Metabolism of carbohydrates

• Detoxification of drugs

• Storage of calcium ions

Cell size calculation formula

V = 4/3 x pi x r^3

What are flagella

Motility structures present in some animal cells and made from microtubules within an extension of the plasma membrane

Prokaryotic cell examples

Bacteria and Archaea

Eukaryotic cell examples

protists, fungi, plants, animals

Endosymbiotic relationships

Symbiogenesis is the leading evolutionary theory of the origin of prokaryotic and eukaryotic cells

What is the endosymbiotic theory?

theory that eukaryotic organelles such as mitochondria and chloroplasts from ancient free living prokaryotes invaded primitive eukaryotic cells

-proposes the ancestor of mitochondria were oxygen using non-photosynthetic prokaryotes that were taken into host cells while the ancestors of chloroplasts were photosynthetic prokaryotes

Endosymbiont meaning

Cell living within another cell

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

What is the cytoskeleton

a network of fibers extending throughout the cytoplasm

Function of ribosomes

protein synthesis, they are complexes made out of ribosomal RNA

Cilia and flagella

hairlike structures that extend from the surface of the cell, where they assist in movement, and contain microtubules

Chloroplast function

Site of photosynthesis in plants

centrosome

A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. A centrosome has two centrioles.

Centrioles

Within centrosomes and composed of nine sets of triplet microtubules arranged in a ring

Cell motility

Ability of a cell to move

Cell fractionation

takes cells apart and separates the major organelles from one another

Are body mass and surface area squared or cubed

• Body mass is volume and cubed

• Surface area is squared

Ameboid motility

Spectrum of migration modes that enables a cell to move in the obstacle of strong, specific adhesion

9+2 pattern

ring of 9 microtubule doublets surrounding central pair of microtubules