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
