Midterm 1 Flashcards
Define Tissue
Groups of cells with the same function ( e.g. nerve cells)
Define organ
Structure composed of several different types of tissues (e.g. heart)
nucleotide
- Adenine
- Guanine
- Thymine
- Cytosine
What is a gene?
Segments of DNA molecule that code for a particular protein.
What is the correct sequence of DNA to protein?
What are the 3 domains that all living things can be grouped into?
- Bacteria
- Archaea
- Euarya
What are the main steps in the scientific method?
- Make observations
- Ask a question
- Form Hypotheses (multiple hypothesis) using inductive reasoning (based on observations)
- Make predictions using deductive reasoning (based on hypothesis)
- Test using controlled experiments
Define independent variable
The variable that is manipulated
Define control treatment
Experimental subjects exposed to “normal” level of independent variable.
Define experimental treatment(s)
Experimental subjects exposed to different levels of independent variable.
Define dependent variable
After experiment has taken place, the dependent variable is what happens as a result of various levels of independent variable.
Define comparative test
Experimental subjects that were “naturally” exposed to various levels of independent variable.
- What if results are as predicted?
- What if results are not as predicted?
- Hypothesis is “consistent” with evidence
- Hypothesis is “rejected” and think up new hypotheses
Note: We can never PROVE that a hypothesis is true! All we can do is reject incorrect hypotheses, and find hypotheses that are consistent with the evidence.
What makes a hypothesis “scientific”?
It has to be testable, that is, potentially able to be rejected.
Define macromolecule
“Big”, more than 1,000 atoms
Note: Most proteins, nucleic acids, and carbohydrates are macromolecules
Define Polymer
Long chainlike molecule consisting of monomers linked together by covalent bonds
How are monomers linked together to form a polymer?
Covalent Bonds
How are proteins polymers made?
Covalently bonded amino acid monomers
How many different types of amino acid monomers exist?
20
How are nucleic acids polymers made?
Covalently bonded nucleotide monomers
How are carbohydrate polymers made?
Covalently bonded monosacchardies
How are polymers built?
Dehydration reaction which removes an H2O molecule to form a new bond. Monomers are added to the chain
How are polymers broken down?
Hydrolysis reaction which breaks covalent bonds by adding an H2O molecule.
Define polypedtide
A polymer of up to 20 different kinds of amino acid monomers.
What determines protein structure?
Side chain (R)
How are amino acids linked together?
By a covalent bond between an amino group and carboxy group
Define Peptide Bond
A bond between an amino group and a carboxyl group.
Note: Two or more linked amino acids form a polypeptide
What is the difference between a protein and polypeptide?
Polypeptide - a polymer of amino acids
Protein - one or more polypeptides that are folded or coiled into a complex 3-D shape.
What is Primary Structure (1º)
The sequence of amino acids in the polypeptide chain.
Note: The order of amino acids with their particular side chain determines the protein’s structure at next levels.
What is secondary structure (2º)
Regular, repeating coiling or folding patterns in a polypeptide chain. Hydrogen bonds between parts of polypeptide backbone.
What is tertiary structure (3º)
3-D foldings of polypeptides existing secondary structure stabilized by interactions between the side-chains.
What is Quaternary Structure (4º)
If protein consists of two or more polypeptides form this particular structure.
Note: Most proteins don’t have quaternary structure since they are composed of only one polypeptide.
What is the main determanant of higher levels of structure, and thus function, of a protein?
Primary structure
Note: a difference in a single amino acid in primary structure will effect higher levels.
Example: Sickle Cell
What are the 3 parts that make up a nucleotide?
- Nitrogen-containing Base (AGCTU)
- Pentose (5-carbon) Sugar (RNA-ribose, DNA-deoxyribose)
- Phosphate group
What is the difference between a nucloside and a nucleotide?
Nucleoside = one base + one sugar
Nuclotide = one nucloside + a phosphate group
How are nucleotides linked to each other?
A covalent bond between a phosphate group of one and the sugar group of the next.
This bond is called a phosphodiester bond. Creating a “sugar-phosphate” backbone, with bases sticking out the side.
The 5’ end has a phosphate group and the 3’ end has a hydroxyl group (OH)
What is DNA composed of and how is it oriented?
DNA is composed of two strands of nucleotides oriented in opposite directions.
How are two strands of DNA held together?
By hydrogen bonds between complementary base pairs.
A-T
G-C
Sort DNA bases into purines and pyrimidines.
Purines: Adenine (A) and Guanine (G)
Pyrimidines: Thymine (T) and Cytosine (C)
A-T
G-C
What is the primary purpose of DNA?
Information-containing molecule which is encoded in the sequences of bases (ATGC)
What are the products of DNA replication?
1 DNA double helix produces 2 identical double helices
What is RNA and how is it formed?
A nucleic acid that contains same information as DNA. Formed by transcription from one of the two strands of a DNA double helix.
How is RNA different from DNA?
- Sugars are ribose, not deoxyribose
- Uracil (U) is used instead of thymine
- RNA is single-stranded thus does not form double helices
What are the products of RNA transcription?
1 DNA double helix produces 1 DNA double helix + 1 Single stranded RNA
What is the central dogma of molecular biology?
- DNA can reproduce itself (replication)
- DNA can copy its information into RNA (transcription)
- RNA can specify a sequence of amino acids in a polypeptide (translation)
For the bond between two carbohydrate monomers (monosaccarides), how is it bonded and what is the bond called.
A covalent bond called a glycosidic bond.
Two linked sugars are disaccharides
What are some main functions of lipids?
- Energy source
- Cell membrane structure
- Key base components of important hormones
What are fats (triglycerides) composed of?
Glycerol + 3 fatty acids bound by ester bonds
What are phospholipids composed of?
Glycerol + 2 fatty acids, bound by ester bonds, + 1 phosphate containing compound
How is mRNA translated into polypeptides?
Amino acids attached to tRNA land on mRNA and then attach to the growing polypeptide. This is mediated by a ribososme.
What are tiplet codons?
Sequences of 3 nucleotides that code for a specific amino acid.
Describe the relationship between a protein, polypeptide and amino acid?
Amino acids are the basic unit of proteins.
Amino acids linked together by a peptide bond forms a chain of amino acids called a polypeptide. When the amino acids from different parts of the chain interact with each other and form hydrogen bonds, the polypeptide chain takes on a unique shape, forming a protein.
Why are most cells so small?
Surace area (ability)-r2 / Volume (need)-r3
So as r increases, the need for new material becomes too great for the ability to supply it.
Name 3 things microscopes do
- Magnify - make image larger
- Increase resolution - minimum distance two points can be seen as two distinct objects
- Increase contrast - brightness difference between object and background
What is the difference between light microscopy and electron microscopy?
Light Microscopy uses beams of light : max resolution = 0.2 micro meters
Electron Microscopy uses beams of electrons: max resolution = 0.002 micro meters
Name two types of light microscopy
- Brightfield LM - light passes through specimen
- Fluorescence - light striking specimen excites fluorescent molecules
Name two types of electron microscopy
- Scanning EM - electron beam energizes electrons on specimen surface
- Transmission EM - electrons pass through a thin secion of specimen
Name some common features of Prokaryotic and Eukaryotic cells
- All cells bounded by a selectively permeable plasma membrane (phospholipid bilayer with proteins and molecules embedded)
- All cells contain cytosol
- All cells contain ribosomes made of ribosomal RNA (rRNA) and protein
What is cytoplasm made of?
Cytosol + particles
Name 7 unique featurs of prokaryotic cells
- Very small: 1-10 micro meters
- Unicellular (but often found in groups)
- Various shapes: baccillus, coccus, and spirals
- No membrane bound organelles
- DNA is nucleoid region (not membrane-enclosed)
- Have flagella for movement and fimbriae (pili) for attachment
- Rigid cell wall outside plasma membrane
What is the main difference between cell wall of Bacteria and Archaea
Bacteria - cell wall contains peptidoglycan (lysozyme effective on)
Archaea - cell wall contains pseudopeptidoglycan (lysozyme not effective)
Name unique features of Eukaryotic cells
- Large 10-100 micro meters
- Contains organelles
- Contains cytoskeleton (microfilaments, intermediate filaments, microtubules)
- Contains a nucleus surrounded by 2 phospholipid bilayers
What is a chromosome
Each DNA molecule is called a chromosome
Define chromatin
A double-stranded DNA molecule (chromosome) wrapped around histones
What is the function of the nucleolus?
Make ribosomes
What happens to DNA inside the nucleus?
- DNA replicated
- DNA transcribed into mRNA (which exits to the cytoplasm via nuclear pores)
- Ribosomes are made (in nucleolus) and exit to cytoplasm via nuclear pores
What is endoplasmic reticulum?
Rough ER (ribosomes) - Protein synthesis
Smooth ER - Lipid synthesis, carbohydrate metabolism
What is the Golgi aparatus?
Proteins from ER are sent to golgi aparatus in vesicles for modification/ packaging/ and are sent elsewhere
What are lysosomes?
Membrane-bound vesicles used to digest food/recycle old cell components
What are some key characteristics of mitochondria?
- Perform cellular respiration for energy
- Contain their own DNA and ribosomes (divide independently)
- Contain outer and inner membrane
Note: Found in most all eukaryotes (INCLUDING PLANTS)
What are plastids?
- Only found in plant cells
- Have their own DNA and ribosomes (replicate independently)
eg. chloroplasts, chromoplasts, amyloplasts
Name 3 motor proteins involved in movement in eukaryotic cells
- Myosin - single cells
- Kinesin - organelles
- Dynein - cilia/flagella (9+2 arrangment)