Cell Types and Structure Flashcards
(143 cards)
1
Q
What are the characteristics of life? (8)
A
Cellular respiration, reproduction, metabolism, homeostasis, hereditary, response to stimuli, growth and development, adaptation through evolution.
2
Q
What are the potential origins of life? (3)
A
Generation of biomolecules (hydrothermal vents)
Generation of replicating organisms (chelation)
Panspermia
3
Q
When was the earliest life on earth?
A
4.5 billion years ago
4
Q
What are the 4 things required for natural selection?
A
Variation, inheritance, selection, time
5
Q
What are the three types of organisms?
A
Bacteria, eukarya, and archaea.
6
Q
What type of organism are humans?
A
Eukarya
7
Q
What is endosymbiosis?
A
That mitochondria (proteobacteria) and chloroplasts (cyanobacteria), are derived from bacteria
8
Q
What is the key difference between prokaryotic and eukaryotic cells?
A
Membrane enclosed organelles are present in eukaryotes
9
Q
What are macromolecules mainly composed of?
A
Atoms, giving them a large molar mass. Also monomers joined by covalent bonds.
10
Q
What are the 4 levels of carbohydrates?
A
mono, di, oli, and polysaccharides.
11
Q
What are the functions of carbohydrates? (3)
A
Recognition, energy, structure.
12
Q
What are the 7 types of proteins?
A
Structural, regulatory, contractile, transport, storage, protective, catalytic, toxic.
13
Q
What are the 3 functions of lipids?
A
Structural, regulatory, energy
14
Q
What must a cell do? (5)
A
Manufacture cellular materials, obtain raw materials, remove waste, generate required energy
15
Q
What is the function of a a plasma membrane?
A
Provide special conditions within the cell, act as a semi-permeable barrier.
16
Q
What is the arrangement of the phospholipid bilayer?
A
Hydrophilic head on the outside of the layer and the tail are between them. Fatty acids affect membrane fluidity.
17
Q
What can the membrane be affected by?
A
Saturation (when it is packed tightly together, there is less fluidity)
Temperature (higher, more fluidity)
Cholesterol (stabilises fluidity)
18
Q
What are the functions of plasma membrane proteins? (5)
A
Signal transduction (from the body into the cell)
Cell recognition
Intercellular joining
Linking cytoskeleton and extracellular matrix.
Membrane transport (passive and active)
19
Q
What are the channels for moving water across the membrane?
A
Aquaporins
20
Q
What cell is only found in animal cells?
A
Lysosomes
21
Q
What are the 2 cells individual to plant cells?
A
Chloroplast, central vacuole
22
Q
What are the structures in the endomembrane system?
A
Nuclear envelope
endoplasmic reticulum
golgi appartus
vesicles
lysosomes
vacuoles
plasma membrane
23
Q
What are the functions of the endomembrane system?
A
Synthesis of proteins, transport of proteins, metabolism and movement of lipids, detoxification of poisons.
24
Q
What is the process of moving proteins out of a cell?
A
Synthesise (endoplasmic reticulum)
Tag and package (golgi apparatus)
Deliver (vesicles)
25
What is the function of the sER?
Metabolism of carbs
Lipid synthesis
Detoxification of poisons
Storage of calcium ions
26
What is the function of the rER?
Protein synthesis
27
What is the golgi complex structure?
Has polarity, vesicles arrive from the endoplasmic reticulum at the cis face and leave from the trans face.
28
What are the functions of the Golgi complex?
Glycosylation (Addition of carbohydrates to proteins), sorting proteins (by adding molecular markers),
Directing vesicle trafficking
29
What are the types of vesicles?
Membrane bound
Transport
Secretory
Vacuoles
30
What is exocytosis?
Transporting material out of the cell or to the cell surface
31
What is endocytosis?
Taking in of particular molecles
32
What is phagocytosis?
Uptake of food particles
33
What is pinocytosis?
Uptake of extracellular fluid containing various solutes
34
What is receptor-mediated endocytosis?
Specialised form of pinocytosis where receptor proteins are used to selectively capture required solute.
35
What are lysosomes?
Membrane -bound environments specific for enzymes to break down 'stuff' within the cell.
36
What is autophagy?
Breaking down of unwanted cellular material
37
What are the major energy requirements of the cell?
Mechanical work
Making new materials
Transport
Maintain order
38
What is the site of cellular respiration?
Mitochondria
39
How many mitochondria are there in a cell?
1-1000
40
How many membranes does a mitochondria have?
2
41
What are cristae?
Folds of the inner membranes
42
Describe glycolysis
Occurs in the cytosol
Glucose converted to 2 pyruvate molecules (2x 3C)
Generates 2ATP
NAD+ made to NADH
43
Describe Pyruvate Oxidation and the Citric Acid cycle
Occurs in the mitochondrial matrix
Pyruvate is converted to Acetyl CoA (which will then enter the citric acid cycle)
ATP, and NADH and FADH2 (high energy electron carriers will then be produced.
44
Describe Oxidative Phosphorylation parts
Electron transport chain
Chemiosmosis
45
Describe the electron transport chain
Electron carriers take electrons to inner mitochondrial membrane through protein complexes.
This causes protons to be pumped across into the intermembrane space, creating a proton gradient.
46
Describe chemiosmosis
Inner mitochondrial membrane contains ATP synthase.
Proton gradient powers ATP synthesis.
47
How to plant cells absorb energy?
Via chlorophyll located in the thylakoid membrane
48
What occurs in the photosynthetic electron transport chain?
Occurs in the thylakoid membrane
Chlorophyll captures light energy and converts in into chemical energy, these high energy electrons then move through the photosynthetic chain.
49
What happens in the light reactions?
Occurs in the thylakoid membrane
High energy protons pumped to build a concentration gradient.
Photosystem I gives them an energy boost
Photosystem II draws electrons from water (forming oxygen biproduct)
With the proton gradeint we can now move through the ATP synthase to make ATP.
DRAW DIAGRAM (lecture 7)
50
Describe the Calvin Cycle (Carbon Fixation).
Occurs in the stroma.
The output of this is a 3 carbon sugar, that, when combined with another 3 carbon sugar, makes glucose.
DRAW DIAGRAM (lecture 7)
51
What is the purpose of cellulose in the plant cell
Major component of cell wall. It forms microfibrils which are a component of both primary and secondary cell walls.
52
What are the two phases of plant cell walls?
Phase one: microfibrils
Phase two: matrix (pectin polysaccharides and hemicellulose polysaccharides)
53
What is in the matrix of a plant cell?
Hemicellulose (large group of polysaccharides)
Pectin (negatively charged polysaccharides that bind water)
54
What controls the extensibility of the plant cell wall?
Extensin cross-linking reduces extensibility and increases strength. It controls how much a cell can expand, it is rigid in old cells
55
Describe the synthesis of the primary cell wall?
1. Cellulose microfibrils at the plasma membrane
2. Polysaccharides in the Golgi are transported to the wall vesicles
3. Cell wall proteins from the rER, vesicles fuse to the plasma membrane.
56
Describe constitutive exocytosis
Releases extracellular matrix proteins
57
What are the cellulose-producing rosettes?
Proteins that move parallel to the cortical (close to the outside) microtubules. They determine where the cellulose microfibrils are laid down as the cell develops.
58
What determines the shape of a cell?
Where the microtubules are laid down, at different angles to give strength.
59
What are the cell wall functions in terms of cell shape?
Provides structural support.
Prevents excessive water uptake.
60
How do the orientation of microfibrils influence cell morphology?
When they are random the cell will expand equally in all directions
When they are at right angles on the long axis, the cell will expand longitudinally (square).
61
What provides structural support in the cell?
Protoplast being pushed against the cell wall to control rigidity.
62
How does the cell prevent excessive water uptake?
The protoplast expands when water enters the cell and pushes against the cell wall, the cell wall limits the volume of water that can be taken up.
63
What is the purpose of the secondary cell wall?
Not all plants have a secondary cell wall. It provides more structural support than the primary cell wall. Only produced after the growth has stopped.
64
What is the secondary cell wall made up of?
Lignin.
65
What are plasmodesmata?
Intercellular connections that enable cell to cell communication. Allows free exchange of small molecules but prevents organelle movements.
66
Describe the inside vs. the outside of the cell.
Outside (extracellular matrix of glycoproteins)
Inside (Cytoskeleton, support and mobility)
67
Describe the function of a cytoskeleton
Helps maintain cell shape. Highly dynamic and provides stability (has the ability to change)
68
What is the structure of the cytoskeleton? (3)
Microtubules, microfilaments, intermediate filaments.
69
Describe microtubules in the cytoskeleton
Resist compression, help maintain cell shape, composed of tubulin subunits, radiate from a centrosome.
70
Describe how microtubules provides cell motility
Flagella move the cell in snake-like motions, cilia move in rowing-like motion.
71
Describe intermediate filaments in the cytoskeleton.
Various types of proteins supercoiled into cables. They are permanent cellular structures.
They maintain cell shape and anchor organelles.
72
What are the 3 types of cell junctions
Tight, gap, desmosomes
73
Describe tight junctions
Middle seal, form a continous seal. Prevents movement of fluid.
74
Describe desmosomes
Anchoring junction. Strong, connected by intermediate filaments.
75
Describe gap junctions
Ions and small molecules can pass cell to cell.
76
What are most extracellular matrix proteins?
Glycoproteins
77
What are the most abundant ECM glycoprotein?
Collagen
78
What is the purpose of a proteoglycan in ECM
Trap water which subsequently retains tissue shape.
79
What is the purpose of integrins in the ECM?
Providing a communication link
80
Where are ribosomes found?
Attached to the rough ER (bound)
In the cytoplasm (free)
81
What is the function of ribsomes?
Making proteins
82
What is the structure of the nucleus?
Nuclear envelope
Nuclear pores
Contains DNA
Nucleolus
83
What is the structure of the nuclear envelope?
Inner and outer membrane with perinuclear space between. Nuclear laminar
84
What is the nuclear lamina
Lining of inner nuclear envelope, composed of intermediate filaments. It maintains the shape of the nucleus.
85
What happens if the nuclear lamina is defective?
Nuclei are unable to retain a spherical shape and this limits the ability of the affected cells to divide
86
What is a nuclear pore?
Channels that control the movement of molecules in and out of the nucleus
87
What are the two types of movement between the nucleus and cytoplasm?
Nucleus to cytoplasm is tRNA and mRNA
Cytoplasm to nucleus is control signals, building blocks, and energy
88
What is the nucleolus
Responsible for making RNA and ribosomal subunits
89
Describe DNA within the nucleus
Interact with histones to form beads called nucleosomes. Further interaction with histones causes the fibres to coil and form metaphase chromosomes
90
What is a karyotype?
Chromosomes displayed in pairs
91
What is euchromatin and heterochromatin?
Euchromatin contains genes being used by the cell (less dense to be able to access)
heterochromatin more dense and contains genes that are not being used.
92
What was Chargaff's Discovery?
DNA could be genetic material, amounts of A and T (C,G) were the same yet differed between species
93
What did the X-ray diffraction discover?
DNA was a helical structure, it is double-stranded with perpendicular bases.
94
Which bases are made from Pyrindines?
C and T
95
Which bases are made from Purines?
A and G
96
How are nucleotide monomers formed?
With phosphodiester bonds
97
How are DNA strand orientated?
Anti-parralell
98
How many hydrogen bonds are between T and A?
2
99
How many hydrogen bonds between C and G?
3
100
What is the Watson-Crick model of DNA?
Double Stranded helical structure
Sugar-phosphate backbone on the outside
Bases on the inside
Stabilised by hydrogen bonds
Two polynucleotide strands orientated in opposite directions.
101
What kind of replication does DNA go through?
Semi-conservative replication
102
Which way does the parental template synthesise?
3' - 5' direction
103
What does semi-discontinuous mean for replication?
There is a leading and lagging strand
104
What way is the lagging strand synthesised?
In the 5' - 3' direction in Okazaki Fragments
105
What is Primase?
An enzyme that makes an RNA primer to start DNA polymerisation
106
What is a locus?
Position of a gene.
107
What is the purpose of cell divison?
Growth, repair, and developmnt
108
Describe the cell cycle
A cell spends most of its life in interphase, during the G1 phase, there is growth. In S phase, DNA is replicated.
109
Describe Prophase (mitosis)
Chromosomes condense, and sister chromatids stick to each other
110
Describe Prometaphase
Sister chromatids attach to the microtubules.
111
Describe Metaphase (mitosis)
Sister chromatids line up. Centromeres line up
112
Describe Anaphase (mitosis)
Microtubules shorten, ripping the sister chromatids apart.
113
Describe Telophase and Cytokinesis (mitosis)
Separation is complete and nuclear envelope is forming
114
What does mitosis produce?
Identical daughter cells
115
Why is meiosis important?
Because our gametes would be 2n and our embryos would be 4n.
116
What happens in interphase of meiosis?
Homologous diploid chromosomes in parent cell are duplicated into sister chromatids.
117
What happens in meiosis I?
Homologous chromosomes are separated, producing 4 haploid cells with duplicated chromosomes
118
What happens in meiosis II?
Sister chromatids are seperated and 4 haploid cells with unreplicated chromosomes are produced.
119
What happens in Prophase I?
Homologous chromosomes synapse and crossing over between non-sister chromatids occurs at the chiasmata.
120
What is a centromere?
Where the sister chromatids are held together
121
What happens in Metaphase I
Homologous chromosomes line by the chiasmata on the metaphase plate
122
What happens in Anaphase I?
Homologous chromosomes seperate and sister chromatids remain attached.
123
What happens in Telophase I and Cytokinesis?
Haploid cells with duplicated chromosomes are produced.
124
What happens in Anaphase II?
The sister chromatids seperate
125
What is the outcome of meiosis?
4 genetically different daughter cells with n amount of chromosomes
126
What causes down syndrome?
Aneuploidy, abnormal amount of chromosome 21. Nondisjunction or failure of chromosomes to separate during meiosis.
127
What is Klinefelter Syndrome
XXY
128
What is polyploidy?
Possession of multiple sets of chromosomes
129
What is Turner Syndrome?
XO
130
What are the 4 types of chromosomal aberrations?
Deletion, Inversion, duplication, and translocation
131
What is the cause of familial downsyndrome?
Translocation of chromosome 21 onto 14.
132
What is a Barr body?
Condensed (inactive) X chromosomes, XY will have 0, XX will have 1, and XXX will have 2.
133
What leads the progressive addition of new nucleotides?
DNA polymerase III
134
What marks the starting point for nucleotide addition?
Primase enzyme making RNA primer
135
What unwinds to gives two parental templates?
Helicase
136
What releases tension generated by the unwinding of the DNA helix
Topoisomerase rejoining NDA strands.
137
What prevents unwound single-stranded DNA from reforming and protecting it from degradation?
Singles-stranded DNA binding protein
138
What removes RNA primer and fills the gap with NDA nucleotides?
DNA polymerase I
139
What joins the end of newly synthesised fragments?
DNA ligase
140
What is Exonuclase?
Nuclease that removes DNA errors during DNA replication. Only the base is removed.
141
What is endonuclease?
Nuclease that repairs errors after replication, removing it and then the polymerase makes new DNA.
142
What is PCR?
Polymerase Chain Reaction. In vitro method of making DNA for medical applications.
143
What is the function of polymerase I?
Removes RNA primers and replaces the gap with DNA nucleotides.
