Semester One Biology Study Guide
Characteristics of Life and Nature of Science:
What does science always begin with?
An observation
What is a question statement?
A question that relates to the observation being made, but that also relates to the reason for
carrying out the experiment.
This statement always varies based on the experiment.
What are controlled, dependent, and independent variables?
Control – does not change, serves as a basis for comparison
Dependent (responding) – changes in response to the independent variable
Independent (manipulated) – purposely changes by investigator and is measured over course of
investigation
What is the difference between the control and experimental group?
Control group does not receive experimental treatment and experimental group does.
What is the difference between an observation and an inference?
Observation is the process of gathering information or data, and inference is making some
decision based on the gathered information or data.
What are the components of the Nature of Science?
1)
2)
3)
4)
5)
Tentative
Empirically-based
Subjective
Involves human inference, creativity
Socially and culturally embedded
What is the correct format of a hypothesis?
If ________, then __________.
What are the 8 characteristics of all living things?
1)
2)
3)
4)
5)
6)
7)
8)
Contain DNA
Reproduce
Respond to their environment
Obtain energy
Maintain stability
Grow and develop
Made of cells
Evolve
Cell Biology:
What is the difference between prokaryotic and eukaryotic cells?
Prokaryotic – mostly single-celled, DNA in cytoplasm, no membrane bound organelles
Eukaryotic – DNA in nucleus, membrane bound organelles
Both – Have cell membrane and DNA
What are the differences between plant and animal cells?
Plant cells – cell wall, chloroplasts, rigid shape
Animal cells – centrioles, more irregular shape
Methods of transport:
Diffusion: movement of molecules from an area of high concentration to low
Passive: transport that does not require the cell to expend energy
Active: transport that requires the cell to expend energy
Osmosis: diffusion of water through a selectively permeable membrane
Hypertonic: concentration of solute is higher outside the cell than inside (cell shrinks)
Hypotonic: concentration of solute is lower outside the cell than inside (cell expands)
Isotonic: concentration of solute is even on both sides of the cell (cell unchanged)
What is the cell membrane made of? What part is hydrophilic and what part is hydrophobic?
A phospholipid bilayer made of lipids with proteins and carbohydrates spread throughout.
Lipid heads are hydrophilic and face out, tails are hydrophobic and face towards the inside
Macromolecules:
What are the four macromolecule? Give an example of each.
Nucleic Acids – DNA and RNA
Proteins – Hemoglobin, Enzymes
Lipids – Fats, Oils
Carbohydrates - Glucose
What are their monomers?
Nucleic Acids – Nucleotides
Proteins – Amino Acids
Carbohydrates - Monosaccharides
What are the parts of each monomer? (If applicable)
Nucleotides – 5 carbon sugar, phosphate group, nitrogenous base
Amino Acid – carboxyl group, amino group, R-group
Photosynthesis and Cell Respiration:
What is the energy transformation that takes place during photosynthesis?
Light energy from the sun is converted into chemical energy within the bonds of glucose.
Explain how a tree obtains its mass.
Trees obtain their mass from the CO2 that they absorb from the air. The carbon from this
molecule is used to build other larger molecules within the tree as it grows and develops. Some
of these are starch and cellulose, which are large carbohydrates.
Where do each of these processes take place?
Photosynthesis takes place in the chloroplasts, in the thylakoids and the stroma. Cellular
respiration takes place in the cytoplasm and mitochondria. Within the mitochondria it takes
place in the mitochondrial matrix and the inner membrane.
What are the reactants and products?
Photosynthesis: CO2 + H2O --- glucose + O2
Cell Respiration: glucose + O2 ----- H2O + CO2
What is the difference between aerobic vs. anaerobic respiration?
Aerobic respiration requires oxygen to take place and anaerobic respiration takes place in the
absence of oxygen.
What is fermentation? When does it occur? What are the two types? What are the products
of each type?
Fermentation is a process of anaerobic respiration which is the primary method of respiration
for some single celled organisms and is also the type of respiration the multicellular organisms
go through when there is not enough oxygen in the blood stream to carry out aerobic
respiration.
The two types are lactic acid fermentation and alcoholic fermentation.
The product of lactic acid fermentation is lactic acid and the products of alcoholic respiration
are CO2 and ethyl alcohol.
Mitosis and Meiosis:
When does crossing over take place?
Prophase I of Meiosis I
What happens in each phase? Focus on most important details.
Prophase – nuclear envelope breaks down, spindles form and migrate to opposite ends of cell,
chromatin condenses into chromosomes
Metaphase – chromosomes line up at equator of cell, spindle fibers attach to centromeres
Anaphase – sister chromatids are separated at centromeres, each chromatids is pulled apart
towards opposite ends of the cell
Telophase – cell in a peanut shape, 2 nuclear envelopes begin to form around chromosomes on
opposite ends of the cell
Cytokinesis – cytoplasm is pinched in half
What are the products of each?
Mitosis – 2 genetically identical daughter cells that are diploid
Meiosis – 4 genetically difference daughter cells that are haploid
What type of cells are involved?
Mitosis – Somatic cells
Meiosis - Gametes
What does it mean for a cell to be diploid? Haploid?
Diploid cells contain the total amount of chromosomes; in humans this is 46
Haploid cells contain half the total number of chromosomes; in humans this is 23
What are the two main parts of the cell cycle? What happens in each?
Interphase – cell is growing, DNA is replicates, transcription and translation takes place
Cell division – Mitosis and Meiosis
Genetics:
What is the difference between heterozygous and homozygous?
Heterozygous – a description of an organism that has two different alleles for one trait
Homozygous – a description of an organism that has two identical alleles for one trait
What is the difference between phenotype and genotype?
Phenotype – the physical characteristic of an organism
Genotype – the genetic makeup of an organism
How are Punnett squares used? Be able to use them to solve simple genetics problems.
Punnett squares are use to determine the probability that a certain trait will be expressed given
the arrangement of the parent alleles.
What are genes? What are alleles?
Genes – a section of DNA that carries encoded information about a specific trait (information
for a protein)
Allele – one of a number of different forms of the same gene for a particular trait
What does it mean for an allele to be dominant? Recessive?
Dominant – a form of a trait that is expressed even if present with a contrasting recessive allele
Recessive – a form of a gene that is only expressed when two copies are present
DNA Structure and Function:
History (Franklin, Chargaff, Watson and Crick)
Franklin – used X-ray diffraction to suggest the structure of the DNA molecule
Chargaff – determined that the percentage of adenine = thymine in multiple samples of DNA in
different living things, from this it was determined that the percentage of cytosine = guanine
Watson and Crick – published the first papers on the double helix structure of DNA and won the
Nobel Prize for this discovery
Describe the double helix structure of DNA. What are its parts? How is it arranged?
The double helix can be described as two strands of nucleotides that resembles a twisted
ladder. Each strand is composed of several nucleotides with the sugar and phosphate molecules
making up the backbone and the nitrogenous bases making up the rungs of the ladder. The
nitrogenous bases face the inside of the molecule. The bases have weak hydrogen bonds
between them that are strong enough to hold the two strands together but weak enough that
they can be broken during replication and transcription.
What are the differences between DNA and RNA?
RNA is a single strand
DNA is double stranded
RNA contains uracil and not thymine
RNA contains the sugar ribose
DNA contains the sugar deoxyribose
Explain the principle of base pairing and give the appropriate base pairs.
Only certain nitrogenous bases can form bonds between them, they are adenine with thymine
and cytosine with guanine
Transcription and Translation:
What are the main types of mutations?
Substitution – one base is substituted for another
- Missense: substitution changes the amino acid chain
- Nonsense: substitution changes amino acid to a stop
- Silent: substitution does not change the amino acid chain
Insertion – a base is inserted
Deletion – a base is deleted
Both insertions and deletions cause a frame shift mutation where the entire reading frame is
shifted which causes all amino acids from the mutation forward to be altered
What happens during transcription? Include location, enzymes involved, etc.
A sequence of DNA (a gene) is transcribed into a complimentary strand of mRNA by the enzyme
RNA Polymerase. This happens in the nucleus.
What happens during translation? Include location, enzymes involved, etc.
The transcribed mRNA leaves the nucleus after RNA splicing and attaches to a ribosome in the
cytoplasm. It is then read one codon at a time. As it is read the corresponding anti codon is
matched to it from a transfer RNA which brings with it the corresponding amino acid that
matches the codon being read. This happens until a stop codon is reached, at which point the
mRNA is released along with the newly formed polypeptide chain.
What are the three types of RNA and what do they do?
Messenger RNA: carries message of DNA to the rest of the cell
Transfer RNA: brings amino acids to the ribosomes, contains anti codon
Ribosomal RNA: makes up a ribosome along with several other proteins
What is a codon? What is an anti-codon?
Codon: sequence of three nucleotides along a strand of mRNA, which corresponds to one
amino acid
Anti-codon: sequence of three nucleotides on a transfer RNA which aids in matching up the
correct amino acid that goes with the codon being read in the ribosome
What is DNA composed of?
Two strands of nucleotides which are a molecule of 5 carbon sugar, a phosphate group, and a
nitrogenous base.
What is the process of DNA replication? What is(are) the end products? What enzymes are
involved?
During DNA replication the enzyme DNA helicase unwinds the double strand of DNA. Once the
strands are separated, DNA polymerase goes along the template strands and matches the
corresponding base pairs. This happens in hundreds of places in Eukaryotic organisms and each
section of replication is called a replication fork. Once completed, the end product is two
strands of DNA that are identical to the parent strand.
******Be able to transcribe and translate a strand of DNA and recognize types of mutations.
Writing portion: Describe the Central Dogma of Biology.
Describe how the double helix structure of DNA matches it’s function.