bsc1005 exam 2

i need a 100 on ts pls

What is the defining characteristic that distinguishes prokaryotes from eukaryotes?

The presence or absence of a nucleus. Prokaryotes lack a nucleus; eukaryotes have one.

What are two key structural differences between prokaryotic and eukaryotic cells besides the nucleus?

Eukaryotes have internal organelles like mitochondria and chloroplasts; prokaryotes do not.

How is microbial DNA organized in prokaryotes?

as a single circular strand of DNA, sometimes with additional plasmids.

What process do bacteria use to reproduce?

Binary fission

How long does it take for a happy E. coli cell to divide in the lab?

Every 20 minutes.

What is the estimated number of bacteria in the human colon?

About 38 trillion.

What is the approximate ratio of bacterial cells to human cells in the body?

1.3:1

What is the human microbiota or microbiome?

All microorganisms (bacteria, fungi, algae, protozoa) that live in harmless association with the human body.

What was the primary goal of the Human Microbiome Project (2008)?

To identify a core set of microbial taxa present in healthy individuals

How many people and sample sites were involved in the Human Microbiome Project?

300 people, 15 to 18 body sites, over 11,000 samples.

Where in the body do microbial communities vary the most and least?

Most in skin and oral samples; least in the GI tract.

What type of microbes dominate the gut microbiome?

Obligate anaerobes

What functions do gut microbes perform?

Aid digestion, generate nutrients from indigestible substrates, and synthesize vitamins B and K.

What is the microbiome-gut-brain axis?

A bidirectional communication system between the gut and brain involving the vagus nerve, neurotransmitters, and hormones.

What evidence supports a link between gut microbes and depression?

Mice transplanted with microbes from MDD patients showed more anxiety.

What is dysbiosis?

A microbial imbalance that can negatively affect health.

What is the main reason humans need to eat?

To obtain energy and essential nutrients that the body cannot synthesize on its own.

What are the three main types of macronutrients?

Carbohydrates, proteins, and fats.

What are the two main types of micronutrients?

Vitamins and minerals.

Which macronutrient is the body’s primary energy source?

Carbohydrates.

What is a simple sugar?

A single-molecule sugar, such as glucose or fructose (a monosaccharide).

What is a disaccharide?

A sugar made of two linked monosaccharides, like sucrose.

What is a complex carbohydrate?

A polysaccharide such as starch or fiber made of many sugar units

What is a saturated fat?

A fat molecule with no double bonds between carbon atoms; usually solid at room temperature.

What is an unsaturated fat?

A fat molecule with one or more double bonds; usually liquid at room temperature.

What is a trans fat and why is it harmful?

An artificially hydrogenated fat linked to increased risk of heart disease.

What are essential amino acids?

Amino acids that cannot be made by the human body and must come from food.

What makes a protein “complete”?

It contains all nine essential amino acids in sufficient quantities.

Why are vitamins considered essential micronutrients?

They are organic compounds required for vital metabolic reactions, and most cannot be made by the body.

Why must we get vitamins from our diet?

The body either cannot produce them at all or not in adequate amounts.

What does it mean when a food is unprocessed?

The food is in its natural state with no additives or modifications.

What qualifies as a processed food?

A food altered for preservation, safety, or flavor (e.g., frozen vegetables, bread).

What is an ultra-processed food?

A food created through industrial processes and containing additives like preservatives, colors, flavors, or emulsifiers.

Give an example of an ultra-processed food.

Soda, chips, instant ramen, or packaged cookies.

What are some components of a healthy diet according to the slides?

Whole grains, fruits, vegetables, lean proteins, healthy fats, and limited ultra-processed foods.

What is homeostasis?

The body's ability to maintain stable internal conditions despite external changes.

What is a negative feedback loop?

A regulatory mechanism where a stimulus triggers a response that counteracts the original stimulus to maintain balance.

Give an example of a negative feedback loop in the body.

Regulation of blood glucose levels using insulin and glucagon.

What happens in the body when blood glucose is high?

The pancreas releases insulin, which directs the liver and muscles to store glucose as glycogen, lowering blood sugar.

What hormone is released when blood glucose is low?

Glucagon.

What does glucagon do?

It signals the liver to break down glycogen and release glucose into the blood, increasing blood sugar levels.

What is diabetes mellitus?

A condition characterized by prolonged high blood glucose (hyperglycemia) due to impaired insulin regulation.

As of 2012, what percentage of the U.S. population had diabetes?

9.3%, or approximately 29.1 million children and adults.

What rank does diabetes hold among causes of death in the U.S.?

It is the 7th leading cause of death.

What is Type 1 diabetes?

A condition where the body does not produce insulin; usually develops in childhood and is thought to have genetic and environmental causes.

What is Type 2 diabetes?

A condition where the body becomes resistant to insulin, often associated with poor diet, lack of exercise, and obesity.

What are some symptoms of diabetes?

Frequent thirst and hunger, frequent urination, fatigue, blurred vision.

What are some long-term health effects of diabetes?

Kidney damage, nerve damage, eye damage (retinopathy), increased risk of cardiovascular disease, and higher likelihood of limb amputation.

How is Type 1 diabetes treated?

With lifelong supplemental insulin injections.

How is Type 2 diabetes treated?

With lifestyle changes such as diet and exercise; if those are ineffective, medication is used.

What is obesity?

A medical condition involving excessive body fat accumulation, typically defined as a BMI of 30 or higher.

What are two primary methods used to assess obesity?

: Body Mass Index (BMI) and body fat percentage.

What are some health risks associated with obesity?

Increased mortality, heart disease, Type 2 diabetes, joint issues, and stroke.

How many deaths per year in the U.S. are estimated to be linked to obesity?

Around 300,000.v

What is the estimated medical cost of obesity-related care in the U.S. (2008 dollars)?

About $147 billion annually

What factors contribute to obesity?

oor diet, sedentary lifestyle, genetics, and gut microbiome composition

What is gout?

A form of inflammatory arthritis caused by a buildup of uric acid in the blood.

What triggers gout attacks?

Uric acid crystals forming in joints and being attacked by the immune system.

What are the symptoms of gout?

Sudden joint pain, redness, swelling, usually in the big toe.

What types of food are strongly associated with gout?

Alcohol, sugary drinks, red meat, seafood, and organ meats.

What dietary factors can help prevent gout?

Consuming dairy, vitamin C, and coffee; maintaining a healthy weight.

How is gout treated?

Pain medication and steroids; prevention through lifestyle changes.

Where is DNA found in the cell?

Inside the nucleus of eukaryotic cells.

What is the structure of DNA?

A double helix made of two strands of nucleotides twisted around each other.

what are the three components of a nucleotide?

A phosphate group, a deoxyribose sugar, and a nitrogenous base.

What are the four nitrogenous bases in DNA?

Adenine (A), Thymine (T), Cytosine (C), Guanine (G).

Which bases pair together in DNA?

A pairs with T, and G pairs with C.

What type of bond holds DNA base pairs together?

Hydrogen bonds

How is DNA different from RNA?

DNA is double-stranded, uses thymine, and contains deoxyribose; RNA is single-stranded, uses uracil, and contains ribose.

Why is complementary base pairing important?

It ensures accurate DNA replication and proper mRNA transcription.

What is the central dogma of biology?

Information flows from DNA → RNA → Protein.

What is transcription?

The process where DNA is used to make messenger RNA (mRNA).

Where does transcription occur?

In the nucleus

What enzyme is responsible for transcription?

RNA polymerase

What is translation?

The process of converting mRNA into a protein using ribosomes

Where does translation occur?

In the cytoplasm, at the ribosomes

What is a codon?

A three-nucleotide sequence on mRNA that codes for a specific amino acid

What is an anticodon?

A three-nucleotide sequence on tRNA that pairs with a codon during translation

What is the role of mRNA in protein synthesis?

It carries the genetic code from DNA to the ribosome

What is the role of tRNA in protein synthesis?

It delivers amino acids to the ribosome and matches them to the codon using its anticodon

What is the role of ribosomes in translation?

They read the mRNA and link amino acids together to form proteins

What are proteins made of?

Long chains of amino acids

Why is a protein’s 3D shape important?

Its shape determines its function and how it interacts with other molecules

What causes the shape of a protein to form?

Interactions between amino acids, such as hydrogen bonds and hydrophobic interactions.

What is a phenotype?

The observable physical and physiological traits of an organism, determined by gene expression and environmental influences.

How does DNA influence phenotype?

DNA contains genes that code for proteins, which carry out functions that shape the organism’s traits.

What is the process from DNA to phenotype?

DNA → mRNA (transcription) → protein (translation) → physical/functional trait.

What is a genetically modified organism (GMO)?

Any organism whose genetic material has been altered using genetic engineering techniques

How are GMOs created in the lab?

By inserting, deleting, or modifying genes within the DNA of an organism using tools like restriction enzymes, plasmids, and CRISPR

What is recombinant DNA?

DNA formed by combining genetic material from two different sources

How are insulin-producing bacteria created?

The human insulin gene is inserted into bacterial DNA via a plasmid, allowing the bacteria to produce insulin

What are some benefits of GMO crops?

Increased yield, pest resistance, longer shelf life, drought tolerance, and enhanced nutrition.

What are some concerns or criticisms of GMO use?

Potential allergies, loss of biodiversity, pesticide resistance, unknown long-term health effects, and ethical issues.

What is transgenic biotechnology?

A form of genetic engineering where genes from one species are inserted into a different species.

How does selective breeding differ from genetic engineering?

Selective breeding uses naturally existing traits over many generations; genetic engineering directly changes the DNA for immediate effect.

What is gene therapy?

The medical use of genetic engineering to insert normal genes into cells to treat or prevent disease.

What is preimplantation genetic screening (PGS)?

A process that tests embryos for genetic traits or diseases before implantation during in vitro fertilization (IVF).

How can gene therapy affect human phenotypes?

By correcting faulty genes, it can restore normal function and prevent or cure genetic disorders.

How does PGS allow selection of human phenotypes?

Parents can choose embryos based on desired or healthy traits, such as avoiding inherited diseases.

What are potential ethical concerns with PGS and gene therapy?

Social inequality, “designer babies,” reduction in genetic diversity, and questions of consent.