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HESI A 2
HESI A2 Study Guide
Biology – Scientific study of life.
A hierarchic organizational system for nomenclature: Kingdom, Phylum, Class, Order, Family, Genus, and
Species.
The kingdom is the largest and most inclusive while species is the most restrictive.
The scientific method:
1. Observation: New observations made/ previous data collected and studied.
2. Hypothesis: Statement or explanation of certain events or happenings.
3. Experiment: Repeatable procedure of gathering data to support or refute the hypothesis
4. Conclusion: Where the date and its significance are fully explained.
The most significant aspect of water is the polarity of its bonds that allow for hydrogen bonding between
molecules.
Several resulting benefits of hydrogen bonding (intermolecular bonding):
1. Waters high specific heat capacity. (specific heat – amount of temp needed to raise temp of 1
gram to 1 degree Celsius). Due to waters (H2O) high specific heat it’s able to resist changes in
temperature and can stabilize environments.
2. Hydrogen bonding also results in strong cohesive (two molecules of likeness stick together) and
adhesive (two molecules attract that are different) properties.
Cohesion example – water tends to run together on newly waxed car.
Adhesion example – When water is spread on the wall some sticks.
- When water freezes it’s known as lattice crystal (only solid that floats on water).
3. The polarity of water also allows it to act as a versatile solvent.
Biologic Molecules include: Carbohydrates, lipids, proteins, and nucleic acids.
1. Carbohydrates – generally long chains or polymers of sugar. The most important functions:
storage, structure, and energy. Carbohydrates form the backbone of DNA and RNA.
2. Lipids (AKA Fats) – Saturated fats contain no double bonds hydrocarbon tail, as a result saturated
fat are solid a room temp and related to cardiovascular problems. Unsaturated fats: have one or
more double bond.
- Phospholipids – two fatty acids varying in length bonded to a phosphate group. Phosphate group
is charged and therefore polar and soluble in water which is important for cellular membranes
which creates a barrier to protect the cell.
- Steroids – lipids that are important because they are a precursor to most hormones and drugs.
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3. Proteins – Most significant to cellular function and are polymers of 20 molecules called amino
acids. Proteins are largest biologic molecule and are used to catalyze reactions with enzymes.
Nearly all cellular function is catalyzed by some type of enzyme.
4. Nucleic acids – Important for a cells inheritance. DNA: Contains code necessary for replication.
RNA is used to transfer info from DNA to protein level and as a messenger in most species of
genetic code.
Metabolism – is the sum of all chemical reactions that occur in an organism. In a cell, reactions take
place in a series of steps known as metabolic pathways from high energy to low energy.
The Cell – Is the fundamental unit of biology. There are two types of cells: Prokaryotic and Eukaryotic.
- Prokaryotic cells: lack a defined nucleus and do not contain membrane bound organelles.
- Eukaryotic Cells: Have a membrane bound enclosed nucleus and a series of membrane bound
organelles that carry out the functions of the cell. The eukaryotic cell is more complex than
prokaryotic.
Several organelles functioning in a cell:
1. Nucleus – contains DNA of the cell organized in masses known as chromosomes. Chromosomes
contain all genetic info for regeneration (replication and repair) of the cell and instructions for
the function of cells.
2. Ribosomes – organelles that read RNA produced in the nucleus and translate genetic instructions
to produce proteins. Cells with a high rate of protein synthesis tend to have large numbers of
ribosomes.
- Ribosomes found in two places: Bound ribosomes found attached to endoplasmic reticulum (ER)
and free ribosomes are found in cytoplasm.
- Rough ER: responsible for protein synthesis and membrane protection.
- Smooth ER: lacks ribosomes and functions as detoxification and metabolism of multiple
molecules.
3. Golgi Apparatus – Packaging, processing, and shipping organelle. Transports proteins from the ER
throughout the cell.
4. Lysosomes – intracellular digestion takes place here. Lysosomes can hydrolyze (with hydrolytic
enzymes) proteins, fats, sugars, and nucleic acids. Lysosomes normally have an acidic
environment (around 4.5 PH)
5. Vacuoles – membrane enclosed structures, process of phagocytosis (eating of other cells) takes
place here. Uptake of food through the cell membrane creating food vacuole. Plant cells have
central vacuole that function as storage, waste, disposal, protection, and hydrolysis.
6. Mitochondria and chloroplast – Produce cell energy:
- Mitochondria - are found in most eukaryotic cells and are the site of cellular respiration.
- Chloroplast – are found in plants and are the site of photosynthesis.
7. Cellular membrane – most important component of a cell contribution protection,
communication, and the passage of substances into and out off a cell.
- Cell membrane is composed of a bilayer of phospholipid with protein, cholesterol, and
glycoproteins peppered throughout.
- Phospholipids are amphipathic molecules creating bilayers making it selectively permeable.
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8. Cellular respiration: Two catabolic pathways that lead cellular energy production: cellular
respiration and fermentation. Cellular respiration produces far more energy that it’s anaerobic
counterpart, fermentation.
- Respiration formula: C6H12O6 + 6O2 6CO2 + 6H2O
- There complex steps to cellular respiration: ATP – energy currency of a cell, NADH – reducing
agent and is a vehicle of stored energy (this molecule is a precursor to greater amounts of ATP
being produced in final steps of respiration).
1. Glycolysis – conversion of glucose to pyruvate taking place in the cytosol of the cell and
produces 2 ATP, 2 pyruvate, and 2 NADH molecules.
2. Citric Acid Cycle (Krebs Cycle) – takes place in the matrix of the mitochondria and for 1 single
glucose molecule – 2 ATP, 6 CO2, and 6 NADH molecules are produced.
3. Electron transport Chain – Remarkable energy harvest here – 28 to 32 ATP molecules for
every single glucose molecule. This conversion results in overall ATP production numbers of
32 to 36 ATP molecules for every glucose molecule consumed.
- Photosynthesis – The reverse of cellular respiration:
6CO2 + 6H2O + Light Energy C6H12O6 + 6O2
- The only noticeable difference is light energy.
- Photosynthesis consists of two different stages: light reactions and Calvin Cycle.
1. Light reactions – cell accomplishes production of ATP by absorbing light and converting
energy to split a water molecule and transfer the electron (which creates NADPH).
2. These molecules are then used in the Calvin Cycle to produce sugar. These sugars are
consumed by the organisms or by the plant itself to produce energy by cellular respiration.
Hesi Hint: The raw materials for cellular respiration are Glucose and Oxygen and the products are water,
carbon dioxide, and ATP. The products of cell respiration is oxygen and glucose become the raw materials
of cellular respiration.
Three types of cellular reproduction: Asexual and sexual reproductions – Binary fission, mitosis, and
meiosis.
Two types of asexual reproduction are binary fission and mitosis.
1. Binary fission – Chromosomes bind to the plasma membrane where it replicates. Then cell
pinches in two producing two identical cells.
2. Mitosis – Occurs in 5 stages Prophase, Prometaphase, Metaphase, Anaphase, and Telophase
before pinching in two identical cells in a process called cytokinesis.
- Prophase – the chromosomes are visibly separate, and each duplicated chromosome has two
noticeable sister chromatids.
- Prometaphase – The nuclear envelope begins to disappear, and the chromosomes begin to
attach to the spindle forming along the axis of the cell.
- Metaphase – All chromosomes align along the metaphase plate or the center of the cell.
- Anaphase – Chromosomes start to separate. In this phase the chromatids are considered
separate chromosomes.
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- Telophase – The final phase with chromosomes gathering either side of the now separation cell.
This is the end of mitosis.
- The second part of mitosis is known as cytokinesis: During this phase the cell pinches in two
creating two separate identical cells.
- Sexual reproduction: two cells contribute genetic material, resulting in significantly greater
variation. This process is called meiosis! Two distinct stages known as meiosis 1 and 2 resulting in
4 daughter cells. Each of these daughter cells contain half as many chromosomes as the parent.
Preceding these events is period called interphase.
- Interphase – Chromosomes are duplicated during meiosis and the cell prepares for division.
- The significant difference between meiosis and mitosis occurs in prophase 1. During this phase
chromatids of homologous chromosomes cross at numerous sections. Small sections of DNA are
transferred between chromosomes resulting in increased genetic variation.
- Genetics – Gregor Mendel discovered the basic principles of genetics using garden peas with a
tool known as the Punnett square.
1. Alleles – Alternative versions of a gene and can be one of two types: dominant and
recessive. If both alleles are the same type they are known as homozygous and if they are
different they are known as heterozygous. Dominant alleles are capitalized, and recessive
alleles are lower case.
2. Genotype – the combination of alleles
3. Phenotype – what traits will be expressed
- DNA is the genetic material of a cell and is the vehicle of inheritance. Watson and Crick
described the structure of DNA to be double helical structure that contains the four nitrogenous
bases: adenine, thymine, guanine, and cytosine.
- Each base form hydrogen bonds with another base of complimentary strand.
1. Adenine bonds with thymine.
2. Guanine bonds with cytosine.
- Transcription: an RNA strand, complimentary to the original strand of DNA, is produced. The
piece of genetic material produced is called messenger RNA (mRNA). The RNA strand has
identical bases of DNA except for uracil, which is substituted for thymine.
- Every group of three bases along the stretch of RNA is called a codon and each of these codes for
a specific amino acid. The anticodon is located on the unit called transfer RNA (tRNA), which
carriers specific amino acid.
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HESI A 2
HESI A2 Study Guide
Biology – Scientific study of life.
A hierarchic organizational system for nomenclature: Kingdom, Phylum, Class, Order, Family, Genus, and
Species.
The kingdom is the largest and most inclusive while species is the most restrictive.
The scientific method:
1. Observation: New observations made/ previous data collected and studied.
2. Hypothesis: Statement or explanation of certain events or happenings.
3. Experiment: Repeatable procedure of gathering data to support or refute the hypothesis
4. Conclusion: Where the date and its significance are fully explained.
The most significant aspect of water is the polarity of its bonds that allow for hydrogen bonding between
molecules.
Several resulting benefits of hydrogen bonding (intermolecular bonding):
1. Waters high specific heat capacity. (specific heat – amount of temp needed to raise temp of 1
gram to 1 degree Celsius). Due to waters (H2O) high specific heat it’s able to resist changes in
temperature and can stabilize environments.
2. Hydrogen bonding also results in strong cohesive (two molecules of likeness stick together) and
adhesive (two molecules attract that are different) properties.
Cohesion example – water tends to run together on newly waxed car.
Adhesion example – When water is spread on the wall some sticks.
- When water freezes it’s known as lattice crystal (only solid that floats on water).
3. The polarity of water also allows it to act as a versatile solvent.
Biologic Molecules include: Carbohydrates, lipids, proteins, and nucleic acids.
1. Carbohydrates – generally long chains or polymers of sugar. The most important functions:
storage, structure, and energy. Carbohydrates form the backbone of DNA and RNA.
2. Lipids (AKA Fats) – Saturated fats contain no double bonds hydrocarbon tail, as a result saturated
fat are solid a room temp and related to cardiovascular problems. Unsaturated fats: have one or
more double bond.
- Phospholipids – two fatty acids varying in length bonded to a phosphate group. Phosphate group
is charged and therefore polar and soluble in water which is important for cellular membranes
which creates a barrier to protect the cell.
- Steroids – lipids that are important because they are a precursor to most hormones and drugs.
Downloaded by Calvin mbukuli ()
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3. Proteins – Most significant to cellular function and are polymers of 20 molecules called amino
acids. Proteins are largest biologic molecule and are used to catalyze reactions with enzymes.
Nearly all cellular function is catalyzed by some type of enzyme.
4. Nucleic acids – Important for a cells inheritance. DNA: Contains code necessary for replication.
RNA is used to transfer info from DNA to protein level and as a messenger in most species of
genetic code.
Metabolism – is the sum of all chemical reactions that occur in an organism. In a cell, reactions take
place in a series of steps known as metabolic pathways from high energy to low energy.
The Cell – Is the fundamental unit of biology. There are two types of cells: Prokaryotic and Eukaryotic.
- Prokaryotic cells: lack a defined nucleus and do not contain membrane bound organelles.
- Eukaryotic Cells: Have a membrane bound enclosed nucleus and a series of membrane bound
organelles that carry out the functions of the cell. The eukaryotic cell is more complex than
prokaryotic.
Several organelles functioning in a cell:
1. Nucleus – contains DNA of the cell organized in masses known as chromosomes. Chromosomes
contain all genetic info for regeneration (replication and repair) of the cell and instructions for
the function of cells.
2. Ribosomes – organelles that read RNA produced in the nucleus and translate genetic instructions
to produce proteins. Cells with a high rate of protein synthesis tend to have large numbers of
ribosomes.
- Ribosomes found in two places: Bound ribosomes found attached to endoplasmic reticulum (ER)
and free ribosomes are found in cytoplasm.
- Rough ER: responsible for protein synthesis and membrane protection.
- Smooth ER: lacks ribosomes and functions as detoxification and metabolism of multiple
molecules.
3. Golgi Apparatus – Packaging, processing, and shipping organelle. Transports proteins from the ER
throughout the cell.
4. Lysosomes – intracellular digestion takes place here. Lysosomes can hydrolyze (with hydrolytic
enzymes) proteins, fats, sugars, and nucleic acids. Lysosomes normally have an acidic
environment (around 4.5 PH)
5. Vacuoles – membrane enclosed structures, process of phagocytosis (eating of other cells) takes
place here. Uptake of food through the cell membrane creating food vacuole. Plant cells have
central vacuole that function as storage, waste, disposal, protection, and hydrolysis.
6. Mitochondria and chloroplast – Produce cell energy:
- Mitochondria - are found in most eukaryotic cells and are the site of cellular respiration.
- Chloroplast – are found in plants and are the site of photosynthesis.
7. Cellular membrane – most important component of a cell contribution protection,
communication, and the passage of substances into and out off a cell.
- Cell membrane is composed of a bilayer of phospholipid with protein, cholesterol, and
glycoproteins peppered throughout.
- Phospholipids are amphipathic molecules creating bilayers making it selectively permeable.
Downloaded by Calvin mbukuli ()
, lOMoARcPSD|23318784
8. Cellular respiration: Two catabolic pathways that lead cellular energy production: cellular
respiration and fermentation. Cellular respiration produces far more energy that it’s anaerobic
counterpart, fermentation.
- Respiration formula: C6H12O6 + 6O2 6CO2 + 6H2O
- There complex steps to cellular respiration: ATP – energy currency of a cell, NADH – reducing
agent and is a vehicle of stored energy (this molecule is a precursor to greater amounts of ATP
being produced in final steps of respiration).
1. Glycolysis – conversion of glucose to pyruvate taking place in the cytosol of the cell and
produces 2 ATP, 2 pyruvate, and 2 NADH molecules.
2. Citric Acid Cycle (Krebs Cycle) – takes place in the matrix of the mitochondria and for 1 single
glucose molecule – 2 ATP, 6 CO2, and 6 NADH molecules are produced.
3. Electron transport Chain – Remarkable energy harvest here – 28 to 32 ATP molecules for
every single glucose molecule. This conversion results in overall ATP production numbers of
32 to 36 ATP molecules for every glucose molecule consumed.
- Photosynthesis – The reverse of cellular respiration:
6CO2 + 6H2O + Light Energy C6H12O6 + 6O2
- The only noticeable difference is light energy.
- Photosynthesis consists of two different stages: light reactions and Calvin Cycle.
1. Light reactions – cell accomplishes production of ATP by absorbing light and converting
energy to split a water molecule and transfer the electron (which creates NADPH).
2. These molecules are then used in the Calvin Cycle to produce sugar. These sugars are
consumed by the organisms or by the plant itself to produce energy by cellular respiration.
Hesi Hint: The raw materials for cellular respiration are Glucose and Oxygen and the products are water,
carbon dioxide, and ATP. The products of cell respiration is oxygen and glucose become the raw materials
of cellular respiration.
Three types of cellular reproduction: Asexual and sexual reproductions – Binary fission, mitosis, and
meiosis.
Two types of asexual reproduction are binary fission and mitosis.
1. Binary fission – Chromosomes bind to the plasma membrane where it replicates. Then cell
pinches in two producing two identical cells.
2. Mitosis – Occurs in 5 stages Prophase, Prometaphase, Metaphase, Anaphase, and Telophase
before pinching in two identical cells in a process called cytokinesis.
- Prophase – the chromosomes are visibly separate, and each duplicated chromosome has two
noticeable sister chromatids.
- Prometaphase – The nuclear envelope begins to disappear, and the chromosomes begin to
attach to the spindle forming along the axis of the cell.
- Metaphase – All chromosomes align along the metaphase plate or the center of the cell.
- Anaphase – Chromosomes start to separate. In this phase the chromatids are considered
separate chromosomes.
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- Telophase – The final phase with chromosomes gathering either side of the now separation cell.
This is the end of mitosis.
- The second part of mitosis is known as cytokinesis: During this phase the cell pinches in two
creating two separate identical cells.
- Sexual reproduction: two cells contribute genetic material, resulting in significantly greater
variation. This process is called meiosis! Two distinct stages known as meiosis 1 and 2 resulting in
4 daughter cells. Each of these daughter cells contain half as many chromosomes as the parent.
Preceding these events is period called interphase.
- Interphase – Chromosomes are duplicated during meiosis and the cell prepares for division.
- The significant difference between meiosis and mitosis occurs in prophase 1. During this phase
chromatids of homologous chromosomes cross at numerous sections. Small sections of DNA are
transferred between chromosomes resulting in increased genetic variation.
- Genetics – Gregor Mendel discovered the basic principles of genetics using garden peas with a
tool known as the Punnett square.
1. Alleles – Alternative versions of a gene and can be one of two types: dominant and
recessive. If both alleles are the same type they are known as homozygous and if they are
different they are known as heterozygous. Dominant alleles are capitalized, and recessive
alleles are lower case.
2. Genotype – the combination of alleles
3. Phenotype – what traits will be expressed
- DNA is the genetic material of a cell and is the vehicle of inheritance. Watson and Crick
described the structure of DNA to be double helical structure that contains the four nitrogenous
bases: adenine, thymine, guanine, and cytosine.
- Each base form hydrogen bonds with another base of complimentary strand.
1. Adenine bonds with thymine.
2. Guanine bonds with cytosine.
- Transcription: an RNA strand, complimentary to the original strand of DNA, is produced. The
piece of genetic material produced is called messenger RNA (mRNA). The RNA strand has
identical bases of DNA except for uracil, which is substituted for thymine.
- Every group of three bases along the stretch of RNA is called a codon and each of these codes for
a specific amino acid. The anticodon is located on the unit called transfer RNA (tRNA), which
carriers specific amino acid.
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