OSAT - Biological Science

Ionic bonds

occurs when one atom transfers electrons to another

Describe an anabolic reaction in metabolism

Anabolic reactions involve the synthesis of complex molecules from simpler ones, often requiring energy input.

Describe the 2nd law of thermodynamics

indicates that energy transformations increase entropy and some energy is lost as heat, making processes less than 100% efficient.

How does the second law of thermodynamics apply to biological systems?

Biological systems increase entropy in their surroundings to maintain organization within themselves.

According to the second law of thermodynamics, which of the following statements is true about biological systems?

The second law of thermodynamics states that the total entropy of an isolated system must increase over time.

What macromolecule is primarily responsible for catalyzing biochemical reactions in cells?

Protein, specifically enzymes

How is a molecule considered organic?

If it contains carbon atoms bonded to hydrogen

Which property of water is primarily is a result of hydrogen bonding?

Adhesion

How does cooperative binding affect enzyme activity?

enables the enzyme to bind more efficiently to additional substrate molecules after the initial substrate molecule binds.

Which cellular organelle is primarily responsible for the production of ATP through oxidative phosphorylation?

Mitochondrion

In which part of the cell does the citric acid cycle occur?

Mitochondrial matrix

What processes produces the most ATP during aerobic respiration?

Oxidative phosphorylation

What processes do organisms use to produce organic molecules from inorganic compounds, such as hydrogen sulfide?

Chemosynthesis

Which molecule is the primary product of the Calvin-Benson cycle?

G3P

What best describes the role of NAD+ in cellular respiration?

NAD+ acts as a coenzyme that carries electrons during glycolysis and the citric acid cycle.

What factor would most likely decrease the activity of an enzyme by altering its shape?

Extreme pH levels

How does the presence of an enzyme affect the energy profile of a chemical reaction?

It decreases the activation energy required for the reaction

What is the primary effect of a competitive inhibitor on an enzyme-catalyzed reaction?

A competitive inhibitor competes with the substrate for the active site, thus affecting enzyme activity.

In which phase of cellular respiration is the majority of NADH produced?

Citric acid cycle

Which of the following organelles is responsible for protein synthesis in a eukaryotic cell?

Ribosome

Which of the following statements about the structure of the plasma membrane is true?

It contains proteins that can move within the lipid bilayer.

Which component of the cell provides structural support and aids in intracellular transport?

Cytoskeleton

Which organelle is primarily involved in modifying, sorting, and packaging proteins for secretion?

Golgi Apparatus

describe cytokinesis in animal cells and in plant cells?

Plant cells form a cell plate during cytokinesis, while animal cells form a cleavage furrow.

describe a negative-feedback mechanism in the human body?

The release of insulin to decrease blood sugar levels after eating

Describe the process of exocytosis?

the process of a cell releasing substances when a vesicle fuses with the cell membrane.

example of a positive feedback mechanism in humans?

Clotting of blood by the release of platelets

What is a positive-feedback in biology

amplify the response to a stimulus, such as in the case of blood clotting where an initial platelet plug formation promotes further clotting.

What role do cell surface proteins play in the maintenance of a cell’s internal environment?

They facilitate the transport of molecules into and out of the cell.

Endocytosis

process that involves the cell membrane engulfing extracellular material to bring it into the cell?

How do cells typically respond to external signals such as hormones?

By altering the permeability of the cell membrane

Facilitated diffusion

processes involves the movement of molecules from an area of higher concentration to an area of lower concentration without the use of energy?

What prevents lysis in plant cells in a hypotonic solution?

Maintaining a rigid cell wall to counteract osmotic pressure

What mechanism typically maintains osmotic balance in a cell in a hypotonic environment?

Active transport of solutes out of the cell

What structure is primarily involved in the attachment of animal cells to the extracellular matrix?

Hemidesmosomes

Chromosomes are maximally condensed at this stage

Metaphase

Chromosomes de-condensation happens during this phase

Metaphase

During this step the nuclear membrane breaks down

Prometaphase

After meiosis 1, each daughter cell contains

One homolog of each homologous pair of chromosomes

Crossing over happens during which phase of meiosis

Prophase 1

How does crossing over contribute to variation

It creates genetic material that is different from the parents

A haploid gamete has how many sets of chromosomes

1

What is cell differentation

Generic embryonic cells becoming specialized cells

In context of population genetics, what does it mean if a population is in a state of evolutionary stasis

The allele frequencies in the population are remaining relatively constant over many generations

Physical barriers prevent gene flow between separated populations allowing them to evolve independently over time

Geographic isolation

In a study of adaptation, what type of isolation is occurring when two groups of insects inhabit the same tree but do not interbreed bc they have developed different mating rituals

Reproductive isolation

If the frequency of dominant allele is represented by peptide and the recessive by q, which condition must be met for a population to avoid speciation and remain in genetic equilibrium?

Large population size with no migration or selection

What is the primary tool for determining the exact order of nucleotides in a genome

DNA sequencing

This technique involves taking single stranded DNA and allowing it to bond with a complentary strand or a probe

DNA Hybridization

The following is an example of what: Restriction enzymes are used as molecular scissors to cut insulin hene from human DNA and to cut a piece of bacterial DNA (plasmid)

1. Ligation: the human insulin is gene is inserted into the bacterial plasmid, creating “recombinant DNA”

2. Transformation: recombinant DNA inserted back into bacterium

3. Fermentation: placed in large tank where they divide rapidly. As they grow using their own genetic instructions they also express the human gene

Genetic engineering

The first stage of the Calvin cycle

Carbon fixation

The Calvin Cycle is responsible for the synthesis of organic molecules. In which specific part of the chloroplast does it take place?

Stroma

In the process of cellular respiration, which metabolic pathway occurs within the cytoplasm and does not require the presence of oxygen

Glycolysis

Describe the role of the Proton gradient established across the inner mitochondrial membrane?

It is driving the synthesis of ATP via ATP synthase

During heavy exercise, if oxygen delivery to muscle cells cannot keep pace with energy demand, the cells will shift to which process to continue producing ATP

Lactic acid fermentation

The total yield of ATP from the complete oxidation of one molecules of glucose is much higher in aerobic respiration than in anaerobic respiration. Approximately how many ATP are produced in the aerobic process compared to anaerobic

30-32 is 2

How do the light products of the light-dependent reactions of photosynthesis relate to the Calvin Cycle

They provide the chemical energy and reducing power needed to build sugars

First part of Protein Synthesis

Transcription

What happens during transcription

DNA unwinds and acts as a Template. An enzyme (RNA polymerase) uses one strand of the DNA as a template to create a complementary strand of mRNA. The mRNA carries the genetic message out of the nucleus and into the cytoplasm to find a ribosome.

Where does transcription take place

In the Nucleus

Translocation takes place where

In the cytoplasm at the ribosomes

What is the second step of protein synthesis

Translocation

What happens during translocation

The rRNA forms structure of the ribosome, which is where the protein is assembled. The tRNA molecules bring specific amino acids to the ribosome. As the ribosome moves along the mRNA the amino acids are linked together by peptide bonds to form a chain. Then the resulting chain folds into a specific 3 dimensional shape such as an alpha helix or pleated sheet to become a functional protein

What is the lack operon in E. Coli?

Usually turned off but can be turned on when a specific molecules (lactose) is present.

What are the components of the lac operon

1. Promoter (where RNA polymerase binds)

2. Operator (the on/off switch)

3. 3 structural genes that code for enzymes used to break down lactose

What happens in Lac operon if lactose is absent

A regulatory protein called a repressor binds to the operator, this physically blocks RNA polymerase from moving down the DNA, preventing production of enzymes. This saves the cell energy since there is no lactose available to digest.

What happens in Lac operon when lactose is present

Lactose molecules bind to the repressor protein, causing it to change shape and release its grip on the operator.

Nonnuclear Inheritance

Is the transmission of genetic information that is located outside of the cells nucleus

Nonnuclear inheritance role in traits

They are essential for an organisms phenotypic expression (the observable traits)

What happens to the DNA strips during DNA replication

Each of the 2 “unzipped” original strands act as a template. New nucleotides are brought in to pair with these original strands forming new hydrogen bonds between complementary base pairs. Ending in 2 complete DNA relics.

End result of DNA replication

On original strands and one brand new complementary strand.

How does DNA “unzip” in protein synthesis

They separate just enough for mRNA to be built using one of the DNA strands as a guide. The two original DNA strands zip back up to each other, reforming their original hydrogen bond

What is the role of helicase

It unzips the DNA to be copied or read

Both PKU and Cystic Fibrosis are what type of disorders

Autosomal recessive disorders

What is an autosomal recessive disorder

Individual must inherit 2 copies of the mutated gene (one from each parent)

Law of segregation in geneticd

During formation of reproductive cells (gametes) the two alleges for a trait seperate so thst each gamete carries only one allele for each gene. So essentially its not “purebred” it has a recessive trait

What is carbon fixation

When a CO2 molecules is attached to a 5 carbon sugar (RuBP). It is catalyzed by the enzyme Rubisco. The resulting 6 carbon intermediate is unstable and immediately splits into 2 molecules of 3 phosphoglycerate (3-PGA)

What is Reduction in the Calvin Cycle?

3-PGA receives a phosphate group from ATP and then is reduced by receiving electrons from NADPH. This transforms the 3-PGA into high-energy three-carbon sugar called G3P. While some G3P leaves the cycle to form glucose, most of it stays to keep the cycle running

What is the 2nd stage of the Calvin Cycle

Reduction

3rd cycle of the Calvin Cycle

Regeneration

What happens during the 3rd stage of the Calvin Cycle?

In the final stage, a series of more complex reactions use more ATP to rearrange the remaining G3P molecules back into RuBP, which allows the “cycle” to begin again and accept more CO2

Although the Calvin Cycle uses CO2 and water as raw materials, it relies on what?

Enzymes (like Rubisco) and cellular structures (like the chloroplast).

Interphase contains which phases from the the overall cell cycle

G1, S, G2

What stage does the cell determine if it will continue with division

G1 checkpoint

When checkpoint is p53 genetic critical at

G1 checkpoint

Prophase

Is the first and longest stage of mitosis. Chromosomes form from chromatin.

During prophase what happens to the nucleolus and nuclear envelope

The nucleus fades away and the nuclear envelope breaks down, allowing chromosomes to move freely within the cytoplasm

What forms during prophase in mitosis

Spindle fibers begin to form between two centromeres

What is the final step in prophase

The centromeres begin to move toward opposite poles of the cell, acting as anchors for the spindle fibers that will eventually pull the chromosomes apart

What happens in metaphase

Chromosomes line up in single row in the middle of the cell (metaphase plate)

What happens during Metaphase to the spindle fibers

Each chromosome is attached to spindle fibers coming from the opposite poles, these fibers attach to a specialized protein structure on the centromere called a kinetochore

Metaphase checkpoint

Cell will pause here to ensure each chromosome is properly attached and under tension

Happens before mitosis

Interphase

Mitosis happens during which phase of the over all cell cycle

M Phase

1st stage of mitosis

Prophase

2nd stage of mitosis

Prometaphase

3rd stage of mitosis

Metaphase

4th stage of mitosis

Anaphase

5th stage of mitosis

Telophase