Mid-Term 1 Prep Flashcards
1
Q
What are the 7 characteristics that we can use to define life?
A
GO ERRRA!!!
Order/Organized (usually into cells)
Ability to process energy/metabolize
Growth and Development (increase in complexity)
Ability to reproduce
Response to environmental stimuli
Regulation – homeostasis
Adaptation (long-term)
2
Q
What is the order of biological organization (from molecules to the biosphere)?
A
Chemical:
Molecule
Cellular:
Organelle
Cell
Tissue
Organ
Organ System
Ecological
Organism
Population
Community
Ecosystem
Biosphere
3
Q
What is the first level of organization where the properties of life emerge?
A
The level of the cell.
4
Q
What happens to elements in the ecosystem? (cycle)
A
Matter is continuously recycled in ecosystems.
Producers (plants) create food, consumers eat food and produce waste, which returns some nutrients back to the environment. The rest are stored in the animal until the it dies, then decomposers release the nutrients back to the soil. Plants also decompose eventually.
5
Q
What happens to energy in the ecosystem? (cycle)
A
It enters as sunlight and exits eventually has heat.
Sunlight energy, converted by plants to chemical energy, converted to kinetic energy by animals, eventually much is converted to heat through various metabolic processes.
6
Q
What evidence do we have that shows that all life is unified?
A
The unity of life is based on DNA. There are fundamental similarities among very different kinds of living things.
All organisms use the exact same code (ATCG) to form DNA, the diversity of life arises from differences in DNA sequences.
Bacteria and humans are different because they have different genes, but the instructions on how to “make them” are written in the same language and use the same molecular building blocks.
7
Q
What do we mean when we talk about the diversity of life?
A
There are tons of species that we can group according to similarities and relationships (Bacteria, Archaea, Eukarya). The diversity of life arises from differences in DNA sequences.
8
Q
How does the theory of evolution describe both the unity and diversity of life?
A
There are fundamental similarities among very different kinds of living things. Such basic similarities imply relatedness, therefore a “common ancestry”.
Unity = Descent from a common ancestor.
Diversity = species diverged from their ancestors over time.
9
Q
What is a hypothesis?
A
A testable explanation for a set of observations based on available data. A logical prediction. IF…THEN
10
Q
What do we mean by a controlled experiment?
A
A large number of samples/individuals.
Control groups give you something to compare the experimental groups to.
The experimental group has only one thing (variable) different than the control group.
Randomized (to control for potentially interfering variables) and blinded (to avoid bias)
11
Q
Was mimicry helpful to non-poisonous King snakes in an environment where there were no poisonous coral snakes?
A
No. Mimicry made the king snakes more visible which was only helpful when predators knew to avoid those colour due to the poisonous coral snakes.
12
Q
What is an atom?
A
An atom is the smallest unit of matter which still displays the characteristic properties of an element. Made of protons, neutrons and electrons.
13
Q
What is an element?
A
An element is a substance that cannot be broken down to other substances by ordinary chemical means. All matter is made of elements.
14
Q
What is a molecule?
A
Molecules are formed when 2 or more atoms (of the same element) combine together.
15
Q
What is a compound?
A
A compound is a substance consisting of two or more elements combined in a fixed ratio. Compounds can have very different properties than its individual components.
16
Q
Only _______(#) elements make up 96% of what is inside of life. What are they?
A
Four. Oxygen, Carbon, Hydrogen and Nitrogen. (from biggest to smallest)
17
Q
What elements make up 98% of all living matter?
A
Oxygen, Carbon, Hydrogen, Nitrogen, Phosphorus, and Sulfur! (from biggest to smallest)
CHNOPS!!
18
Q
What goes into carbohydrates and proteins? (Related to: What elements make up 96% of what is inside of life?)
A
Carbohydrates = CHO (Carbon, Hydrogen, Oxygen)
Proteins = primarily CHNO…and a bit
of S. (Carbon, Hydrogen, Nitrogen, and Oxygen… and Sulfur)
19
Q
What are the 3 subatomic particles?
A
Protons, neutrons and electrons.
20
Q
What are the charges of the 3 subatomic particles?
A
Protons are positive.
Neutrons are neutral.
Electrons are negative.
21
Q
What are the sizes of the 3 subatomic particles? Where are they located within the atom?
A
Protons and neutrons are bigger, approximately the same size, and occupy the nucleus.
Electrons are teeny tiny and occupy “orbitals” or “energy shells” around the nucleus.
Atoms are mostly empty space!
22
Q
Which subatomic particle is responsible for defining the element?
A
Protons. All atoms of a particular element have the same number of
protons.
23
Q
Which subatomic particle is responsible for an element’s reactivity?
A
The atom’s reactive properties are based on the electrons.
24
Q
What is the atomic number?
A
The number of protons specific to an element.
For example, carbon has 6 and oxygen has 8.
25
What is the atomic mass?
The mass of a single isotope or single atom. The sum of an atom's neutrons and protons.
i.e. Carbon, with its six protons and six neutrons has an atomic mass of 12
26
What is the atomic weight?
The average weight of an element with respect to all its isotopes and their relative abundances.
27
What is an isotope? Do these behave differently?
An atom with more or less neutrons than normal (normally protons = neutrons). The atom behaves the same as normal but has a different atomic mass. Some may be radioactive.
28
How many electrons fit into a single orbital? How are orbitals related to energy?
Only **two** electrons can occupy an orbital at any one time. Atoms with more than two electrons have a series of orbitals at increasing distances from the nucleus. **The further an electron is from the nucleus, the greater its energy**
29
How many electrons and orbitals fit into the first shell and second shell?
The first shell contains 1 orbital and can hold 2 electrons. The second shell contains 4 orbitals and can hold 8 electrons.
30
What do we call electrons in the outer shell that dictate how the atom reacts?
The outer shell is the valence shell, and the electrons in it are **valence electrons**. They determine the chemical properties of the atom and are available for chemical bonding.
31
What is a stable number of electrons in a valence shell?
Most stable when **full**. Most of the elements important in biology need **eight** electrons in their outermost shell.
32
What are the three basic types of chemical bonds?
**Covalent Bonds** can be nonpolar (equal sharing) or polar (unequal sharing).
**Ionic Bonds** (one donates, one receives, creating ions)
**Hydrogen Bonds**
33
What is a double (or triple) bond?
Formed when atoms share two (or three) pairs of electrons. Prevents rotation unlike single bonds.
i.e. O2 has a double bond.
34
What is electronegativity? How does it affect bonds?
The ability to attract electrons from other atoms in a molecule. The closer the outer shell is to being full the more electronegative the atom. If a bond forms between two atoms with different electronegativities the bond will be "polarized".
35
Do electrons closer to or further from the nucleus have a higher energy level?
The **further** an electron is from the nucleus, the greater its energy.
36
What are polar bonds and why is this important for water (H2O)?
Polar covalent bonds include the **unequal** sharing of an electron.
In H2O the oxygen holds the electrons closer giving it a slight negative change and the hydrogen a slight positive change. This allows water to hydrogen bond!
37
What is a hydrogen bond? What compound is this most relevant to?
A weak electrical attraction between polar molecules. A slightly positive hydrogen of one molecule attracts a slightly negative atom from another molecule. Usually shown as a dotted line.
**Water**'s two hydrogen atoms form a "V" shape. H2O will hydrogen bond to other H2Os.
38
What are some of the unique properties of water because of hydrogen bonding? (7 properties)
Freezing point (O°C) and boiling point (100°C) are higher than expected so it's **usually liquid** (good for chem reactions).
**Universal solvent**.
The most **abundant** liquid.
High **heat of vaporization** (water absorbs lots of heat to evaporate, evaporative cooling) and high **heat capacity/specific heat** (changes temp. slow, buffer).
Strong **cohesion/adhesion**(plants! and water tension/meniscus).
**Ice floats**, it's less dense than the liquid water due to its lattice structure (lake life).
39
What is a solution?
A liquid that is a mixture of 2 or more substances.
40
What is a solvent? What's a common solvent?
The dissolving agent in a solution – usually a liquid. Water is the most versatile solvent known because of its polarity.
41
What is a solute?
A substance that is dissolved in a solution (often a solid).
42
What is the hydrogen ion concentration and pH of pure water?
In one litre of pure water the H+ concentration is 1x10-7 moles and the pH is 7 (neutral).
43
How does the pH (the potential of Hydrogen) scale work?
pH describes how acidic or basic a solution is on a scale of 0 to 14. It is the negative log10 of the hydrogen ion concentration.
Acids = 0 to 7, add H+ to solutions.
Neutral = 7, equal H+ and OH-
Bases = 7 to 14, add OH- to solutions (a.k.a. subtracting H+).
44
How does the pH scale increase/decrease?
It's a logarithmic scale, so every change in pH of 1 unit represents a 10-fold change in the [H+] of a solution.
pH 6 = 10 x more H+ than 7
pH 5 = 10 x 10 = 100 times more H+ than 7
45
What is a buffer? Why is it important?
Buffers are solutions that resist changes in pH when an acid or a base are added to them.
The molecules and chemistry of life function within very narrow ranges of pH.
46
What is the bicarbonate buffer system?
A buffering system in mammalian blood (and seawater). This system is in equilibrium and is reversible. When you add CO2 (by breathing) you shift the equation to the right and get more H+, and vice versa.
47
What causes acid rain? What is it's pH?
Mostly burning fossil fuels (sometimes volcanoes, metal smelting) = sulphurous and nitrous oxides = sulphuric and nitric acids = acid rain, snow, fog, hail, or even dust. Regular rain = pH 5.6, acid rain = pH 4.2 to 4.4
48
What are some of the effects of acid rain?
Additional acid alters the pH of environments. Run off adds toxic elements into aquatic systems. Dissolves shells. Leaches toxins from soil, robs nutrients, makes plants weak. Damages roots, leaves and bacteria.
49
What causes ocean acidification?
The increase in CO2 from fossil fuel burning over the past 150 years. Carbon dioxide dissolves into water and becomes carbonic acid (H2CO3) which adds more H+ to the water.
50
What happens to the pH of the oceans as they become more acidic (or less basic)? What's the approx. ocean pH?
The pH becomes lower. Prior to industrialization, oceans were slightly alkaline with a pH of 8.2, today it is about 8.1 (which is significant, pH is logarithmic).
51
How does ocean acidification affect sea creatures?
A lower pH dissolves **calcium carbonate** shells and exoskeletons.
Coral reefs require carbonate ions for their skeletons. Coral reef ecosystems are safe havens. Many shelled organism are important to food webs.
52
Why is carbon the backbone of so many biologically relevant molecules (4 reasons)?
It's **abundant**; it can form **four covalent bonds**; can easily form and break bonds with **oxygen and other carbons** (important for respiration/ photosynthesis, carbon chains are useful). Carbon is super **versatile** (length, double bonds, branching, rings).
53
How many valence electrons does carbon have? How many bonds does it want?
Carbon has **four electrons** in the outer valence shell, and can form **four covalent bonds**.
54
What is the basic formula for a hydrocarbon?
Contains only hydrogen and carbon. Carbon forms the skeleton or backbone.
55
What is the basic formula for a carbohydrate? Hydrophobic/philic?What are they used for?
Hydrated Carbon – they all contain C and H2O. Contains hydroxyl groups (OH) & carbonyl groups (C=O).
Tend to be hydrophilic due to many OH groups. Used for energy storage (sugars/starches).
56
What is the basic formula for a protein?
Polymers made from various combinations of 20 amino acids. A carbon backbones with a carboxyl (COOH) and amino group (NH2). The carboxyl and amino groups of different molecules are joined to create proteins.
57
What are nucleic acids?
What is their basic formula?
Are macromolecules including Ribonucleic Acid (RNA) and Deoxyribonucleic Acids (DNA). Made of monomers called nucleotides (made of 5C sugar, a phosphate group PO4, and a nitrogen base).
Dehydration synthesis joins nucleotides: sugar to phosphate.
58
What are lipids? What are two common properties between lipids?
Includes compounds commonly known as fats, oils, and waxes. Includes fats (triglycerides), phospholipids and steroids. They are not huge macromolecules. Vary a lot in structure and function but are all hydrophobic.
59
What are the 6 primary functional groups that can be added to carbon skeletons?
**Hydroxyl Group** OH
**Carbonyl Group** C=O
**Carboxyl Group** COOH
**Amino Group** NH2
**Phosphate Group** PO4
**Methyl Group** CH3
Remember N and O are polar and hydrophilic.
60
What is an isomer? What are the three types?
Organic compounds with the same molecular formula, but different structures. They differ in chemical properties despite having the same basic chemistry.
Structural (branching)
Geometric (cis/trans, functional groups around a double bond)
Enantiomers (mirror image)
61
What is a monomer?
A subunit (molecule) that serves as a building block for a polymer (mono = 1)
62
What is a polymer?
A large molecule consisting of many identical or similar monomers (poly = many)
63
What is a macromolecule?
A very large molecule important to biological processes, such as a protein or nucleic acid. (Macro = big)
Polymers are macromolecules.
64
What chemical reaction is used to “stick” monomers together to make polymers?
Dehydration synthesis!
The formation of larger molecules from smaller reactants accompanied by the **loss of a water molecule**.
65
What is a catalyst?
A substance that increases the rate of a chemical reaction without being permanently changed. It's reusable!
66
What is the definition of hydrolysis?
How is this related to polymers and monomers?
The reverse of dehydration synthesis.(Hydro = water, lysis = loosen, dissolve)
Adding water and breaking a bond (and breaking the water into H and OH).
Can break polymers back into monomers.
67
What are monosaccharides? Example?
A class of carbohydrates. Single unit sugars (monomers), basic ratio of 1:2:1 for C:H:O; (i.e., CH2O).
Most common is glucose – C6H12O6 (often in a ring structure).
68
What is a disaccharide? Example?
A class of carbohydrates. 2 monosaccharides joined via dehydration synthesis. i.e. Maltose, Sucrose (NRG transport in plants), Lactose.
69
What is a polysaccharide? Example?
A class of carbohydrates. Very long chains of monosaccharides linked together via dehydration synthesis.
i.e. Starch (plant); Glycogen (animal); Cellulose (plant) and Chitin (animal).
70
What is starch? What is it used for?
The simplest polysaccharide, used as an energy storage molecule in plants. Consists entirely of glucose molecules “stuck” together via dehydration synthesis.
Animals have enzymes to break starch into glucose.
71
What is a glycogen?
A storage polysaccharide of animals, highly branched, most often found in muscle and liver cells.
72
How are glycogen and starch different?
Starch: energy storage in plants, straight (amylose) or branched (amylopectin).
Glycogen: energy storage in animals, highly branched.
73
What is cellulose?
How is it different from starch or glycogen?
Principal component of plant cell walls; most abundant organic molecule on earth; a polysaccharide whose linkages cannot be broken down by most animals; source of insoluble fibre.
74
What do we mean by primary, secondary, tertiary, and quaternary structure of a protein?
**Primary**: Amino acids connected by peptide bonds (a long chain).
**Secondary**: Spirals (Alpha helix) or pleated sheets made by hydrogen bonds.
**Tertiary**: The overall 3D shape stabilized by interactions between R groups.
**Quaternary**: 2 or more 3D tertiary proteins and “sticking” them together to form a larger protein.
75
What holds the secondary structure of proteins together?
Hydrogen bonds between atoms in the protein's backbone. (hydrogen bonds with the electronegative nitrogen and oxygen).
76
What holds the tertiary structure of proteins together?
Interactions between the R groups in the protein. Different groups can form ionic, covalent and hydrogen bonds with each other.
77
What happens when a protein becomes denatured? Why does this happen?
They lose their 3-D shape and their function. Can be caused by acids (pH changes), salts or heat and may be reversible.
78
What do we call the bond that forms between the carboxyl group of one amino acid with the amino group of another?
Amino acids are linked via dehydration synthesis. The bond that forms is called a **peptide bond**.
79
What are some of the functions of proteins (7)?
Enzymes (catalyze/regulate chemical reactions); Transport (across cell membrane); Defensive; Signal (hormones); Receptor (in cell membrane); Contractile (muscle cells); Structural (connective tissues).
80
What are the 4 nitrogenous bases in DNA?
The four bases in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T).
81
What are the 4 nitrogenous bases in RNA?
Adenine (A), cytosine (C), uracil (U), and guanine (G).
82
What is complimentary base pairing? Which bases pair together?
Pairs are joined by hydrogen bonds between the bases.
In DNA:
Adenine (A) and thymine (T) pair.
Cytosine (C) and guanine (G) pair.
RNA, adenine pairs with uracil.
83
What does hydrophobic and hydrophilic mean?
Hydrophobic – “water-fearing”
Hydrophilic – “water-loving”
84
Are lipids hydrophobic or hydrophilic?
Hydrophobic.
85
What class of molecules did we look at that are not considered polymers?
Triglycerides (?)
Fats are not huge macromolecules.
86
What's a triglyceride composed of? What type of bond holds it together?
A glycerol (a 3C alcohol) and 3 long-chain fatty acids. Attached by dehydration synthesis forming an **ester bond**.
87
What is the primary function of fats/triglycerides?
Long-term concentrated energy storage, cushions organs, insulates body, needed for cell membranes.
88
What do we mean when we say fatty acids are saturated? What are they saturated with? Example?
Saturated fats have no double bonds in their fatty acids. This allows them to be saturated with hydrogens.
Mostly animal fats, pack tightly, tend to be solid at room temp.
89
Why do double bonds make fats more likely to be a liquid at room temperature?
The double bond causes a bend or a “kink” that prevents the fatty acids from packing tightly.
90
What is the name of the bond that forms between the carboxyl group of a fatty acid and the hydroxyl group of the glycerol molecule?
An **ester bond** which is created through dehydration synthesis.
91
What is the name of the chemical reaction that joins molecules together? What version of this reaction have we focused on?
Synthesis reactions. This class has focused on dehydration synthesis: the formation of larger molecules from smaller reactants accompanied by the loss of a water molecule.
92
How are phospholipids different from triglycerides? How do they react with water?
They only have 2 hydrogen/carbon tails and add one phosphate (PO4) group.
Has a hydrophilic head and two hydrophobic tails.
93
Why do phospholipids automatically form bilayers or micelles in aqueous solutions? What shape are these formations?
Because of the hydrophilic head and two hydrophobic tails. This is important to cell membranes.
Micelles are round. Bilayers are sheets.
94
A type of lipid where the carbon skeleton contains 4 fused rings is called a ___________.
Steroid.
95
What is cholesterol?
A type of steroid (and therefore a lipid) and an important building block of cell membranes and steroids, including sex hormones etc.
96
Is cholesterol soluble in water?
No, cholesterol is hydrophobic.
97
How is cholesterol transported in the body?
Cholesterol is packaged for transport in **lipoproteins** (fat-proteins).
More protein than fat = high density lipoproteins (HDL).
Less protein than fat = low density lipoproteins (LDL).
98
What's the difference between HDL or LDL? Which is better?
LDL (low-density lipoprotein) leaves more sticky cholesterol build up in arteries while HDL (high-density lipoprotein) can remove build up...if it hasn’t hardened too much.
99
When plaques from excess cholesterol in the blood builds up in artery walls it is called ______.
Atherosclerosis
100
When plaques becomes hardened by fibrous tissue and calcification it is called ___________.
Arteriosclerosis
101
What is the primary cause of a heart attack?
Coronary artery disease (arteriosclerosis in the heart's arteries). Also trans fats can increase the risk of heart disease.
102
What is the primary cause of a stroke?
The arteries of the brain (cerebral arteries) being affected by arteriosclerosis.
103
What did Robert Hooke do?
Coined the term cell.
In 1665, created an illustrated book of microscopic observations.
104
What did Anton van Leeuwenhoek do?
Late 1600s, made the most high-quality lenses of the day, looked at tons of cells (human blood, sperm, pond water), and wrote about it.
105
What is the first postulate of cell theory?
(1839) **all living things are composed of cells**.
106
What is the biogenic law?
(1855) Rudolph Virchow stated that **“all living cells arise from pre-existing cells”**, not spontaneously generated as previously thought.
107
What was Louis Pasteur's experiment and its significance?
(1862) Performed experiments with open and closed sterilized flasks + broth to show that "life" needed a way into the flask to grow.
It proved the biogenetic law.
108
In 1880 August Weissman added another part to cell theory – what was it?
“...cells living today trace their ancestry back to ancient times” i.e., there must be a common ancestral cell.
109
Currently cell theory has 3 main principles…what are they?
All living things are made of cells.
A cell is the smallest unit in a living thing.
All cells come from other cells.
110
Define magnification.
The increase in apparent size of an object. Reported as #x.
i.e. 200x magnification.
111
Define resolution.
A measure of the clarity of an image. The ability of an optical instrument to show 2 nearby objects as separate.
112
The smaller the cell the _____ its surface area to volume ratio. The larger a cell, the _________ its surface area to volume ratio.
Higher; lower.
Large cells have more surface area than small cells, but they have much LESS surface area RELATIVE to their volume than smaller cells do.
113
How do prokaryotic cells differ from eukaryotic cells (5)? How are they similar (4)?
**Both** have a cell (plasma) membrane; one or more chromosomes with DNA; ribosomes to make proteins; cytoplasm.
**Prokaryotes** have no nuclear membrane (DNA is in the nucleoid region); smaller slightly different ribosomes; a rigid cell wall outside of the plasma membrane; a sticky outer coat (capsule) sometimes; much smaller than eukaryotic cells.
114
What organelles have we talked about in eukaryotic cells and what do they do (10)?
**Nucleus** controls all functions of the cell using DNA.
**Ribosomes** make protein.
**Endoplasmic reticulum** makes and transports things.
**Golgi apparatus** finishes, sorts and ships things.
**Lysosomes** digest and recycle.
**Vacuoles** digestion, storage, and osmotic regulation.
**Mitochondria** the powerhouse of the cell.
**Chloroplasts** photosynthesis.
**Cytoskeleton** holds shit together.
**Cilia + Flagella** wiggle wiggle.
115
What’s in the nucleus (5)? What does it do?
**Double membrane/nuclear envelope** holds it together, **nuclear pores** molecules can pass thru, **nucleoplasm** jelly-matrix things "float" it, **chromatin** composed of DNA/chromosomes, **nucleolus** makes special RNA used to create ribosomes.
116
What’s in the nucleolus? What does it do?
Are rich in **RNA**. Makes special RNA used to create ribosomes, the **ribosomal RNA** (rRNA). Proteins interact with rRNA to form subunits of ribosomes. These subunits exit the nucleus and form functional ribosomes.
117
What are ribosomes? Where are they found?
Protein making machines found in the rough endoplasmic reticulum (bound ribosomes) or floating in the cytoplasm (free ribosomes).
118
What is the endoplasmic reticulum (ER)? Where is it located?
An extensive membrane system within the cytoplasm of the cell.
Involved in the synthesis, modification and transport of substances produced in the cell. Connected to the nuclear envelope.
119
What is smooth (SER) and rough endoplasmic reticulum (RER) and what do they produce?
**RER**: has ribosomes that make proteins, modified by the RER, makes a transport vesicle, which goes to the Golgi apparatus.
**SER**: involved in the synthesis of steroid hormones, lipids, oils, and other non-protein substances and in the storage of calcium.
120
What and where is the Golgi Apparatus (GA). What does it do?
A stack of flattened membranous sacs or cisternae close to the nucleus. Continues processes begun in the ER. Sorts and modifies proteins for selective export.
Transport vesicles - cis face (receiving) - modified thru the stacks - exported from trans face (closest to plasma membrane).
121
What’s a lysosome?
Small vacuoles that aid in **cell digestion**. Contain powerful digestive enzymes from the ER/GA. Food vacuoles combine with a lysosome to be digested. Can recycle old organelles.
122
What’s a vacuole? How do vacuoles differ in plant and animal cells?
Large water containing vesicles (Digestion, Storage, and Osmotic Regulation).
Animals: contractile vacuoles help eliminate water from cytoplasm.
Plants: may have digestive functions, contain cell pigments or poisons. Are large and allow plant cells to grow bigger.
123
What are contractile vacuoles and why are they important?
Vacuoles found in many freshwater organisms. Fill with water (from cytoplasm) and contract to expell their contents. Removes water that enters by osmosis from the environment.
124
What are the parts of mitochondria (5)?
**Outer membrane**, **inner membrane** (highly folded) containing the mitochondrial **matrix** (containing mitochondrial DNA + ribosomes). In between membranes is the **intermembrane space**. The folds of the inner membrane are called **cristae** (increase surface area).
125
What are mitochondria? What important cellular process are they involved in?
Energy producing organelles found
in all eukaryotic cells (both plant and animal). The site of **cellular respiration**. Converts energy from
sugars to energy of adenosine
triphosphate (ATP).
126
What are the parts of a chloroplast (5)?
**Inner and outer membrane** with intermembrane space, **stroma** (fluid) inside the inner membrane containing chloroplast’s DNA, ribosomes, enzymes and a third membrane = **thylakoids** (system of flattened disks) that contain thylakoid space and **chlorophyll**. A stack of thylakoids is called a **granum**.
127
What important cellular process are chloroplasts involved in?
Converting solar (light) energy to chemical (sugar) energy via **photosynthesis**.
128
Do animal cells have chloroplasts?
No.
129
What support is there for the theory of endosymbiosis?
Mitochondria and chloroplasts have:
A single circular DNA molecule (similar to prokaryotes); ribosomes similar to prokaryotes; a double membrane and divide independently from the cell.
130
What are the three components of the cytoskeleton? What do they each do?
Smallest to largest:
**Microfilaments** (inside cell membrane, supports cells shape)
**Intermediate Filaments** (reinforces shape, anchors organelles)
**Microtubules** (hollow tubes, maintains shape, makes tracks for organelles to move along).
131
What does the cytoskeleton do? What does it do when combined with motor proteins?
Provides support to cells. Combined with motor proteins, microtubules act as tracks for organelles to move along within the cell – the transport highways of the cell.
132
What are microtubules used to make?
Microtubules make up centrioles (important in cell division), cilia and flagella
133
What is the configuration of centrioles in a cilia and flagella? How does this differ from that in centrioles or basal bodies?
Nine pairs of microtubule doublets for a circular arrangement around a central pair. "Nine-plus-two" (or, 9 x 2 +2) arrangement.
Basal bodies and centrioles have nine triplets of microtubules and no central microtubules. (9 x 3)
134
What are the primary differences between cilia and flagella?
They differ only in length, number per cell and type of motion. Flagella are much longer and fewer than cilia.
Cilia row, flagella undulate.
135
What motor protein is responsible for the movement of cilia and flagella?
**Dynein**. Movement is the result of sliding movements of the protein between microtubule pairs.
136
How do environmental contaminants appear to affect sperm?
Hormonally active chemicals in the environment (like phthalates) interfere with sex hormones and
negatively affect sperm quality.
Lower sperm counts, higher percentages of malformed sperm and reduced motility.
137
What would happen to cilia and flagella if there were no dynein protein arms connecting pairs of microtubules? (as with the rare disease: primary ciliary dyskinesia)
Cilia of the lung and flagella of sperm cannot move, because the microtubules cannot bend. So lungs can’t be cleared and sperm can’t swim!
138
What holds cells together in tissues (in animals)?
The **extracellular matrix**. Made of glycoproteins and strong collagen fibres that helps hold tissues together and support the plasma membrane.
139
What are the three types of cell junctions in animal cells? Describe each.
**Tight** (very close, no leaks, tied by proteins);
**Anchoring** (desmosomes, cells riveted together with keratin proteins anchored in the cytoplasm);
**Gap** (communicating, protein-lined pores connect cells allowing ions to flow through)
140
What type of junction allows for the coordination of heart muscle cells, so they all beat at once?
Gap junctions. The flow of ions through gap junctions of adjacent cells coordinates their contraction.
141
What functions do plant cell walls have?
Skeletal support, preventing enlargement and rupturing of the plant cell in hypotonic solutions; important for absorption, transport and secretion of substances
142
What are plasmodesmata?
Holes in the cell walls of plants that
allow for intercellular communication in plant tissues. Cell membrane and the cytoplasm extend through the plasmodesmata.
143
What organelle controls gene expression?
The nucleus (and ribosomes which operate with RNA instructions).
144
Which organelles are involved in the manufacture, distribution, and breakdown of cellular materials?
The Endomembrane system:
Nuclear envelope;
Endoplasmic reticulum (ER);
Golgi apparatus;
Lysosomes;
Vacuoles; and
Plasma membrane.
145
Which organelles produce energy in plants and animals?
Mitochondria in plants and animals.
Chloroplasts in only plants
146
Which organelles provide structural support, movement and intercellular communication (4)?
Cytoskeleton (microfilaments, intermediate filaments and microtubules), extracellular matrix (in animals), cell junctions (between animal cells), and cell walls with plasmodesmata in plant cells.
147
Which organelles are found only in plants?
Chloroplasts and cell walls.
