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Flashcards in Topic 2 Deck (20):

State Ficks law

Fucks law states:
Rate of diffusion=
area of diffusion surface * difference in conc
Thickness of surface over which diffusion takes place


Describe what's the 'primary structure of a protein'

It's the number and sequence of amino acids in a polypeptide chain


Describe what is meant by the 'tertiary structure of a protein'
Including all bonds

The irregular folding if anpolypetide chain into its overall 3-dimensional shape

The shape is determined by the locations of the bonds between R groups and also the primary structure

Disulphide bonds (between R groups that contain sulphur)

Ionic bonds (between positive and negatively charged bonds)

Hydrogen bonds (between slightly positive and negative R groups)

Hydrophobic interactions (between hydrophobic R groups)


What's the function of phospholipids?

Creates a phospholipid Bilayer, providing a fatty barrier between the inside and outside of cells


Some of the functions of membrane proteins?

-carrier proteins
-Channel proteins


Function of glycoproteins and glycolilpids?

Joins cells together to form tissue
Cell registration


Function of cholesterol in Bilayer

Helps stabilise the membrane
Affects membrane permeability


Define osmosis

Passive, net movement of free water molecules across a partially permeable membrane from a high water conc to low water conc


Describe how substances can be moved across a membrane by facilitated diffusion

Facilitated diffusion is the passive movement of molecules from high to low conc through a protein Channel.

Larger or polar molecules (e.g glucose, amino acids and ions) can pass through the membrane this way


Why can channel proteins only allow one kinda of molecule through

They are a specific shape to one type of molecule


Explain how substances can be moved across a membrane by active transport including protein specificity

The molecule attaches to a binding site (specific to one type of molecule) on the protein, before it is transported through


How dose DNA form a double helix using hydrogen bonds?

Hydrogen bonds form between complementary bases on opposite strands


Name the base pairs and how many bonds they make

A-T (2 hydrogen bonds)
C-G (3 hydrogen bonds)


differences between RNA and DNA

-double polynucleotide chain (double helix)
-pentode sugar is Deoxyribose
-organic bases are A,T,G,C
- DNA is found in the nucleus
-amount is constant for all cells of a species
-one basic form: DNA
-hydrogen bonding between base pairs
-larger than RNA: whole chromosome (many genes)

-single polynucleotide chain
-pentode sugar is ribose
-organic base pairs are A,U,G,C
-made in nucleus b found throughout cell
-amount varies throughout cell
-two basic forms: mRNA and tRNA
-no bonds in mRNA but hydrogen bonds in tRNA
-smaller than DNA: length of one gene


Describe the stages of transcription in the nucleus

1. DNA unwinds from nucleus
2. hydrogen bonds form between two broken DNA strands


Give 2 examples of a large SA in mammalian body to do with gas exchange

A branched system of tubes ending in many alveoli

Many capillaries surrounding the alveoli


Give two examples of a conc gradient adaptation to do with gas exchange

Ventilation, replaces air that has lost some oxygen

Continues blood flow, replaces oxygenated blood with deoxygenated around the lungs


Give 2 examples of a minimised distance of diffusion in gas exchange

Capillary walls are just one cell thick

Alveolar walls are one cell thick


Describe what is meant by the primary structure of a protein

The number and sequence of amino acids in a polypeptide chain


Name the 4 types of bonding involved with the tertiary structure of a protein

Disulphide bonds
Ionic bonds
Hydrogen bonds
Hydrophobic associations