B/B Missed

Comprehensive practice flashcards covering muscle physiology, cellular respiration, viral genetics, hormonal regulation, calcium metabolism, oxidative stress, apoptosis, DNA repair, lipid biochemistry, membrane dynamics, and metabolic pathways as detailed in the lecture transcript.

Under what metabolic conditions does lactic acid fermentation occur?

Occurs when oxygen isn't being used and anaerobic metabolism dominates.

What are the characteristics of Type $IIX$ muscle fibers?

High glycolytic capacity, fast-twitch fibers, few mitochondria, few capillaries.

What defines aerobic muscle in terms of color and components?

Red muscle containing myoglobin, oxygen, many mitochondria, many capillaries, Type $I$ fibers.

What defines white muscle in terms of metabolism and components?

White muscle relying on glycolysis, lactate production, few mitochondria, Type $IIX$ fibers.

In the cross-bridge cycle, what is the role of $ATP$ in relation to actin and myosin?

$ATP$ is required for myosin release from actin.

What is the role of $ATP$ in the power stroke of muscle contraction?

$ATP$ is required for this force-generating step of muscle contraction.

What is the role of $ATP$ in the sarcoplasmic reticulum during muscle relaxation?

$ATP$ is required to pump calcium back into the sarcoplasmic reticulum.

Which neurotransmitter is released by motor neurons to initiate skeletal muscle contraction?

Acetylcholine (ACh)

Which receptor on skeletal muscle binds to Acetylcholine (ACh)?

Nicotinic Receptor

In aerobic respiration, to which pathway does $NADH$ donate its electrons?

Electron Transport Chain (ETC)

What is the terminal electron acceptor in the process of aerobic respiration?

Oxygen

What molecule accepts electrons from $NADH$ during lactic acid fermentation?

Pyruvate

In the reaction $Pyruvate + NADH \rightarrow Lactate + \text{\_\_\_\_}$, what is the missing product?

$$NAD$$

What is the terminal electron acceptor during lactic acid fermentation?

Pyruvate

What are changes to a viral genome that affect its replication called?

Mutations

What is the general term for a substance that causes changes to a viral genome?

Mutagen

Why do viruses lack their own metabolic processes?

They are not living organisms.

What is the term for a mutation that improves viral replication inside a host cell?

Advantageous Mutation

What is the term for a mutation that interferes with viral replication?

Deleterious Mutation

How do thyroid hormones travel through the bloodstream?

They circulate bound to transport proteins.

How does epinephrine circulate within the bloodstream?

It circulates largely free in the bloodstream.

How do peptide hormones typically circulate in the bloodstream?

Water-soluble hormones that circulate mainly in free form.

How do steroid hormones typically circulate in the bloodstream?

Lipophilic hormones predominantly bound to proteins in circulation.

Which glands are involved in the Hypothalamic-Pituitary-Thyroid Axis?

Hypothalamus, pituitary, and thyroid glands.

Which hormone is released by the parathyroid glands to maintain blood calcium levels?

$$PTH$$

How does $PTH$ affect calcium levels via the diet?

$PTH$ increases calcium absorption from the diet.

How does $PTH$ affect calcium levels via the kidney?

$PTH$ increases calcium reabsorption in the kidney.

How does $PTH$ affect calcium levels via bone tissue?

$PTH$ promotes release of calcium from bone.

Which specific cells are responsible for bone resorption?

Osteoclasts

What is a consequence of prolonged exposure to elevated $PTH$ levels?

Increased osteoclasts.

What is the direct result of increased osteoclast activity in skeletal tissue?

Bone Resorption

What occurs when excess reactive oxygen species cause cellular damage?

Oxidative Stress

What is the major source of reactive oxygen species ($ROS$) in cells?

Mitochondrial $ETC$

Name one reactive oxygen species ($ROS$) produced by the $ETC$.

Superoxide

Name a second reactive oxygen species ($ROS$) produced by the $ETC$.

Hydrogen Peroxide

Name a third reactive oxygen species ($ROS$) produced by the $ETC$.

Hydroxyl Radical

Which enzyme is responsible for the removal of hydrogen peroxide?

Peroxidase

Which enzyme is responsible for converting superoxide radicals?

Superoxide Dismutase

A decrease in which $ETC$ complex can lead to increased oxidative stress?

Complex $V$

What is the term for programmed, controlled cell death?

Apoptosis

Besides oxidative stress, what is another primary trigger for apoptosis?

DNA Damage

What molecule is released from the mitochondria to initiate the apoptosis process?

Cytochrome C

What mitochondrial event must occur to allow for the release of Cytochrome C?

Increased Membrane Permeability

Which proteases are activated by Cytochrome C during the process of apoptosis?

Caspases

What is the inactive form of caspases called in healthy cells?

Procaspases

Which DNA polymerase activity removes incorrect bases from the ends of a DNA strand?

Exonuclease Activity

In which direction does exonuclease activity proceed for DNA proofreading?

$$3' \rightarrow 5'$$

Which repair pathway repairs DNA mistakes located in the middle of a strand?

$$BER$$

Which enzymes use endonuclease activity to remove damaged bases from the middle of DNA?

$NER$ Enzymes

What specific enzymatic activity involves removing nucleotides from the middle of a DNA strand?

Endonuclease Activity

Which structural lipids are primarily found in biological membranes?

Sphingolipids

Which broad lipid classification includes both glycerophospholipids and sphingolipids?

Structural Lipids

Which type of lipid is primarily responsible for the storage of energy?

Triacylglycerides

What metabolic process is used to degrade triacylglycerides for energy production?

$\beta$-Oxidation

Identify the hydrolyzable structural lipid that contains two fatty acyl chains.

Glycerophospholipid

Identify the structural lipid that contains only one hydrolyzable fatty acyl chain.

Sphingolipid

What is the nonhydrolyzable backbone found in sphingolipids?

Sphingosine Backbone

Name a nonhydrolyzable structural lipid found within cell membranes.

Cholesterol

What effect does a short chain length have on fatty acid membrane fluidity?

Increases membrane fluidity.

What effect does a long chain length have on fatty acid membrane fluidity?

Decreases membrane fluidity.

How does unsaturation affect membrane fluidity?

Increases membrane fluidity by creating kinks.

What property of a fatty acid is associated with greater membrane rigidity?

Saturation

What does the notation $20:1$ indicate about a fatty acid's structure?

One Double Bond

What structural feature is caused by a double bond in a fatty acid tail?

Kink

Which is more fluid: a $20$-carbon fatty acid tail or a $24$-carbon tail?

$20$-carbon tail

Which is more rigid: a $24$-carbon fatty acid tail or a $20$-carbon tail?

$24$-carbon tail

Which enzyme is responsible for activating fatty acids in the cytosol?

Acyl-CoA Synthase

What is the product formed when a fatty acid reacts with $CoA$ in the cytosol?

Acyl-CoA

Which molecule combines with Acyl-CoA to facilitate its transport into the mitochondria?

Carnitine

What intermediate product is formed when Acyl-CoA reacts with carnitine?

Acylcarnitine

Which transport protein carries acylcarnitine across the inner mitochondrial membrane?

Acylcarnitine Translocase

Which mitochondrial membrane tightly regulates entry into the matrix?

Inner Mitochondrial Membrane

What is the pathway that degrades Acyl-CoA within the mitochondrial matrix?

$\beta$-Oxidation

Which intermediate is found in the $CAC$ and gluconeogenesis but is not involved in fatty acid import?

Oxaloacetate

What happens to DNA duplex stability as the length of the DNA increases?

DNA duplex stability increases.

What factor can destabilize the DNA helix when it undergone extreme changes?

$$pH$$

How does salt concentration influence DNA stability?

Higher values increase DNA stability.

What effect does a lower salt concentration have on DNA?

Decreases DNA stability.

What is the definition of the isoelectric point ($pI$) for a protein?

The $pH$ at which a protein has a net neutral charge.

What is the net charge of a protein when the $pH$ of the environment is lower than the protein's $pI$?

Positively Charged

What is the net charge of a protein when the $pH$ of the environment is higher than the protein's $pI$?

Negatively Charged

What process results in a protein becoming more positively charged by the addition of protons?

Acidification

In which cellular compartment does protein acidification typically occur?

Endolysosome

Which chromatography method is used to bind and separate positively charged proteins?

Cation-Exchange Chromatography

Which metabolic pathway is used to rapidly produce $ATP$ without the use of mitochondria?

Glycolysis

Which pathway's primary function is producing $NADH$ and $FADH_2$ rather than direct $ATP$ production?

$$CAC$$

What is meant by 'increased glycolytic flux'?

An increase in the rate through glycolysis to maintain $ATP$ levels.

In biochemistry, what does the term 'flux' refer to?

The rate through a pathway.

What serves as the major backup source for $ATP$ when oxidative phosphorylation is impaired?

Glycolysis

The inhibition of $PFK-1$ by high levels of $ATP$ is an example of what type of regulation?

Allosteric Regulation

The inhibition of $PFK-1$ by high levels of $ATP$ is an example of what feedback mechanism?

Feedback Inhibition

Which cellular system is responsible for degrading individual proteins tagged with ubiquitin?

Ubiquitin-Proteasome System

Which cellular component is used for the degradation of endocytosed material and organelles?

Lysosome

What is the process by which old or damaged organelles are degraded inside lysosomes?

Autophagy

What is the specific tag added to proteins to mark them for proteasomal degradation?

Ubiquitin

What is the ultimate cellular destination of a ubiquitinated protein?

Proteasome

What is the ultimate cellular destination of an endocytosed receptor?

Lysosome

What is the destination of an old mitochondrion for degradation?

Lysosome

Where are misfolded cytosolic proteins typically sent for degradation?

Proteasome

Give three examples of regulatory proteins that are degraded by the proteasome.

Cyclins, $\beta$-Catenin, $p53$