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Flashcards in Module 2 Deck (83)
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1

Three components of the cytoskeleton

Microfilaments- contractile fibres formed from actin, responsible for cell movement
Microtubules- globular tubular proteins used to form a scaffold-like structure that determines the shape of the cell
Intermediate fibres- give mechanical strength to cells

2

Differences between prokaryote and eukaryote

Pro=no nucleus, circular DNA, non membrane bound organelles, peptidoglycan cell wall

Euk= nucleus, linear DNA, membrane and non membrane bound organelles, chitin (f) cellulose (p) cell wall, no cell wall (a)

3

What elements do carbohydrates have

C H O

4

What elements do lipids have

C H O

5

What elements do proteins have

C H O N S

6

What elements do nucleic acids have

C H O N P

7

Describe ice

(less dense) so molecules spread out
Lattice
Ice forms insulating layer
Water below doesn’t freeze
Many hydrogen bonds between molecules
High specific heat capacity

8

Describe the structure of ice

Between O and H (of adjacent molecules)
Between electropositive and electronegative
Water molecule is polar

9

Explain the importance of water being a solvent

medium for (metabolic) reactions
Transport
in the xylem and phloem
Organisms can absorb minerals
Able to dilute toxic substances
*NOT NUTRIENTS*

10

Describe the test for reducing sugars using colorimeter

Use known concentration of reducing sugars
Heat with Benedict's solution
Changes to brick red
Reading of transmission
Calibration curve

11

Describe amylose

1-4 glycosidic bonds
Helix
More compact
Less soluble

12

Describe amylopectin

1-4 and 1-6 glycosidic bonds
Branched (lots of free ends)
More compact
Less soluble

13

Describe glycogen

1-4 and 1-6 glycosidic bonds
Highly branched and free ends
More compact
Less space needed for it to be stored

14

Describe cellulose

1-4 glycosidic bonds (beta glucose molecules)
Alternate beta glucose molecules are turned upside down
Straight chain
Strong and insoluble

15

Bond of triglyceride

ester

16

Saturated fatty acids

no double bonds

17

Unsaturated fatty acids

double bonds

18

Roles of lipids in living organisms

thermal insulation, energy store, protects vital organs, buyout, water proofing

19

Roles of lipids in cells

electrical insulation in myelin
hormones

20

Describe the primary structure of. a protein

Peptide bonds between amine and carboxyl group
H combines with OH
Condensation reaction
Covalent bond

21

Describe the secondary structure of a protein

hydrogen bonds form causing either an alpha helix or beat pleated sheet

22

Describe the tertiary structure of a protein

Some R groups attract/repel
Disulphide bonds between cysteine
Hydrogen bonds
Ionic bonds between oppositely charged R groups
Hydrophilic R groups on the outside of the molecule
Hydrophobic R groups on the inside of the molecule

23

Describe the quaternary structure of a protein

same interaction in tertiary, but between protein molecules

24

Describe globular proteins

compact, water soluble, normally spherical

25

Insulin

Globular, hormone, therefore precise shape

26

What are conjugated proteins

globular proteins with a prosthetic group

27

Haemoglobin

Sequence of amino acids ,peptide bonds, prophetic haem group

28

Catalase

Enzyme, iron II prosthetic group, breaks down hydrogen peroxide

29

What are fibrous proteins

Long, insoluble molecules due to high proportions of amino acids with hydrophobic R groups in their primary structure

30

Keratin

Present in hair, skin and nails
Strong disulphide bonds forming strong, inflexible and insoluble materials

31

Elastin

Flexible, needed to expand blood vessels and alveoli

32

Collagen

Found in skin, tendons, ligaments
Long polypeptides, in strong rope-like structure, flexible

33

How does a high increase in temperature affect proteins

Increased kinetic energy
Hydrogen bonds break
Change in 3D shape
Denatures

34

State the structure of a nucleotide

Deoxyribose (sugar)
Phosphate (group)
Nitrogenous base

35

Describe the difference between RNA and DNA

Ribose instead of deoxyribose
Uracil instead of thymine
Single stranded instead of double stranded

36

Describe the role of mMRA

Carries the copy of the gene out of the nucleus
Transfers it to ribosome

37

Pyrimidines

Thymine and Cytosine (2 hydrogen bonds)

38

Purines

Adenine and Guanine (3 hydrogen bonds)

39

Describe semi conservative replication

Double helix uncoils by DNA helicase
Hydrogen bonds break
Free nucleotides join by complementary base pairing
Hydrogen bonds reform
Sugar phosphate backbone forms
By DNA polymerase

40

Describe translation

DNA helicase unzips the section of DNA
Free RNA nucleotides base pair with complementary bases (uracil binds to adenine)
Phosphodiester bonds form between the RNA nucleotides by RNA polymerase
mRNA detaches from the template and leaves nucleus via the nuclear pore
(RNA is the same as the coding strand except uracil)

41

Describe transcription

The mRNA binds to the ribosome at its start codon
A tRNA with complementary anticodon binds to mRNA.
The tRNA carries the amino acid
Peptide bonds form between the amino acids, catalysed by peptide transferase
The ribosome then moves along the mRNA, releasing the tRNA

42

What is ATP made up of

A nitrogenous base, pentose sugar and 3 phosphate groups

43

What makes ATP good for releasing energy

Small, water soluble

44

What is the induced fit hypothesis

Where the active site changes shape slightly as the substrate enters

45

Digestion of starch

starch=>(amylose) maltose =>(maltase) glucose

46

Digestion of protein

proteins=>(protease such as trypsin) amino acids

47

Competitive inhibition

Where a molecule/ part of a molecule has a similar shape to the substrate
The substrate is blocked fro entering the active site, preventing the enzyme catalysing the reaction
*reduces rate of reaction but doesn't change Vmax*

48

Non-competitive inhibition

The enzyme binds to the allosteric site
The binding of the inhibitor causes the tertiary shape to change, meaning the active site shape changes
Active site no longer complementary to substrate
*decreases rate and Vmax*

49

What is a cofactor

non-protein helper component for enzymes, loosely bind

50

What is a prosthetic group

required by certain enzymes to catalyse reactions, tightly bound and form a permanent feature of a protein

51

What are coenzymes

derived from vitamins, responsible for transfer of hydrogen atoms between molecules in respiration

52

what are channel proteins

when polar molecules and ions diffuse through membranes (intrinsic protein)

53

what are carrier proteins

when polar molecules and ions diffuse AND are actively transported across a membrane (intrinsic protein)

54

What is a glycoprotein

an intrinsic protein with carbohydrate chains attached

55

What is the role of glycoproteins

Cell adhesion and receptors for cell signalling

56

What is a glycolipid

A lipid with carbohydrate chains attached

57

What is the role of glycolipids

Called cell markers or antigens

58

Describe active transport

ATP binds to carrier protein and is hydrolysed to ADP+Pi
Protein changes shape
Molecule/Ion released to the inside of cell
Phosphate molecule and ADP recombine forming ATP
Carrier protein returns to original shape

59

What is bulk transport

Another type of active transport where large molecules such as enzymes can't move through channel/carrier proteins (endocytosis and exocytosis)

60

Less concentrated solution=
More concentrated solution=

Higher water potential (water moves in)
Lower water potential (water leaves)

61

What happens during interphase?

DNA replication, protein synthesis in cytoplasm, mitochondria grow and divide

62

What happens in the G1 phase

Proteins from which organelles are synthesised are produced and organelles replicate
Cell increases in size

63

What happens in the S phase

DNA replication

64

What happens in the G2 phase

Cell increases in size, energy stores are increased

65

Why does a cell enter G0?

Differentiation, DNA of cell may be damaged, cell too old

66

What is checked at the G1 checkpoint?

Cell size, nutrients and DNA damage

67

What is checked at the G2 checkpoint?

Cell size, DNA replication, DNA damage

68

What is checked at the spindle assembly checkpoint?

That chromosomes are attached to spindle fibres

69

Describe mitosis

Chromatin fibres begin to coil and condense
Nuclear membrane breaks down
attach to spindle;
by centromere;
Chromosomes move to metaphase plate
spindle fibres shorten
chromatids, pulled to opposite poles ;detachment from spindle fibres;
Chromosomes start to uncoil
Nucleolus is formed

70

Describe the role of mitosis

Cell division
genetically identical
growth
repair (of tissues)
asexual reproduction

71

how are cells produced by meiosis may differ from those produced by mitosis

haploid / half genetic information
genetic information not identical
4 cells produced

72

Describe the ways in which genetic variation is produced

Independent assortment of homologous chromosomes;
in metaphase I
and of chromatids in metaphase II
So homologous chromosomes have different alleles
Crossing over in prophase I
so chromatids will have new combination of alleles
Mutation
chromatids will have new combination of alleles
Random fertilisation
Produces large number of allele combinations

73

Describe meiosis 1

P1= same as mitosis except homologous chromosomes pair up forming bivalents and crossing over occurs
M1=homologous pairs of chromosomes meet at metaphase plate. Random orientation of each pair causes independent assortment, resulting in different combinations of alleles.
A1=homologous chromosomes are pulled to opposite poles. Sections of DNA may be exchanged (chiasmata) which forms recombinant chromatids.
T1= same as mitosis

74

Describe meiosis 11

P2=2 chromatids coil and condense, nuclear envelope breaks down
M2=Individual chromosomes meet at metaphase plate. Independent assortment and more genetic variation
A2=results in chromatids of the individual chromosomes being pulled apart to opposite poles
T2=same as mitosis. Cytokinesis occurs resulting in 4 daughter cells that are genetically different and haploid

75

What is a tissue

A tissue is made up of differentiated cells that have a specialised function.

76

What is an organ

An organ is a collection of tissues that work together to perform a particular function

77

What is an organ system

Each organ system is composed of organs working together to carry out a major function in the body

78

What does totipotent mean

These stem cells can differentiate into any type of cell (a zygote)

79

What does pluripotent mean?

these stem cells can form all tissue types but not whole organisms (early embryo)

80

What does multipoint mean

these stem cells can only from a range of cells within a certain type of tissue (haemotopoetic stem cells in bone marrow)

81

Sources of animal stem cells

embryonic stem cells, tissue stem cells (bone marrow)

82

Sources of plant stem cells

meristematic tissue

83

ethics of stem cells

Religious objections, destroying a life,
But can to treatment of many incurable diseases