Biology term 1 y9

Sub-cellular structures

structures found in cells that include the nucleus, mitochondria, chloroplasts and ribosomes

Nucleus

the control centre of the cell

Cytoplasm

the substance found in living cells (outside the nucleus), where chemical reactions take place

Cell membrane

a layer that holds the cytoplasm in a cell and controls what enters and leaves the cell

Mitochondria

the structures in the cytoplasm where energy is produced from chemical reactions

Ribosomes

small structures found in the cytoplasm of living cells where protein synthesis takes place

Cell wall

a protective layer, found outside the cell membrane of plant, fungal and bacterial cells, that helps to support the cell

Cellulose

a carbohydrate that makes up the cell wall of plants

Vacuole

a fluid-filled cavity in a cell that is used for storage and support

Chloroplast

a sub-cellular structure containing chlorophyll, which is found in plants and algae that carry out photosynthesis

Prokaryotic

organisms, such as bacteria, that do not have a nucleus or organelles such as mitochondria

Eukaryotic

cells that have a nucleus and sub-cellular organelles such as mitochondria

flagellum

an organelle that enables movement

slime capsule

slimy layer covering a bacterial cell that prevents cell from drying out and helps cell stick to surfaces

Plasmid

a small circle of bacterial DNA that is independent of the main bacterial chromosome

Resolution

the ability to distinguish two objects from each other

Electron microscope

a device that fires electrons at a specimen to obtain a high resolution image

Chromosomes

long molecules found in the nucleus of all cells; made from DNA

DNA

nucleic acid molecules that contain genetic information and make up chromosomes

Gene

A region of DNA that codes for a specific sequence of amino acids (which chain up to make up a polymer; protien)

Double helix

two linked strands that wound around each other to resemble a twisted ladder in a helix-like shape.

Magnification

The ability to make a small object look bigger

What is the formula for image size?

Imagesize = actual image x magnification

Pili

short, hair-like structures on the cell surface of prokaryotic cells. They can have a role in movement, but are more often involved in adherence to surfaces

protein synthesis

process of making proteins, it occurs in 2 main steps, transcription and translation.

mrna

Messenger rna, is a single strand copy of a dna, its is made because transporting the whole dna would be unnecessary.

Trna

transfer rna is an adaptor molecule that serves as the physical link between the mRNA and the amino acid sequence of proteins. It floats outside of the ribosomes and contains 3 sets of nucleotides called anticodons and each carry an amino acid.

stage 1 (transcription)

the process of when the mrna is created and transported out of the nucleus into the ribosomes. This is carried out by an enzyme which unzips the dna and makes a copy of the relevant strand. This copy is the mrna. The mrna is the transported out of the nucleic pores and into the ribosome.

splicing

the process of when introns are removed and exons are added the the mrna

introns

a region of a gene that does not encode for anything (irrelevant)

exons

a region of a gene that encodes for proteins

stage 2 (translating)

The mrna is is used as a guide to sort the trna into the correct order by reading the mrna 3 nucleotides (triplets) at a time and attaching a trna complementary set of nucleotides (anticodons).In this process, the amino acids that the trna carry are also ordered which makes them join together with hydrogen bonds, making them form a polypeptide. The polypeptide will go on to make a protein.

polypeptide

a chain of amino acids

monomer

a molecule that can be bonded with identical molecules to form a polymer

polymer

a substance made from monomers

order of magnitude

Differences in size are often described as differences in order of magnitude. (example) If you increase a number by one order of magnitude, you are multiplying the number by 10. If you decrease a number by one order of magnitude, you are dividing the number by 10, which is equivalent to multiplying by 0.1

Scanning electron microscope

A type of electron microscope that uses a beam of electron across the surface of a specimen where reflected electrons are collected to produce an image

Transmission electron microscope

A type of electron microscope that uses a beam of electron to pass through a thin sample. The electrons are detected and creates an image.

Electron microscope

A microscope that uses a beam of electrons.

.images created are in black and white and specimen need to be dead as electrons pass through a vacuum

.expensive and not portable

.difficult preparation (thin slices especially tem)

Max magnification of electron microscope

x500,000

Max magnification of light microscope

x600

Max resolution of light microscope

0\.2 um (micrometers)

Max resolution of electron microscope

0\.1 nm (nanometers)

Light microscope

A type of microscope that passes light through an object placed on a slide. The object is observed through the objective and eyepiece lens that magnify the object.

.it can view image in natural colours

.it is cheap and portable

.easy to prepare ( slide w specimen and specific stain)

Methylene blue

A stain that highlights the nucleus of an animal cell

Iodine

A stain that highlights plant cell nuclei

crystal violet

A stain that highlight bacterial cell walls

Nucleotide

A phosphate group, ribose sugar and nitrogenous base

Nitrogenous bases

Adenine, thymine

Cytosine, guanine