Which statement about the following pathway is false? a. A...

Which statement about the following pathway is false? a. A mutation for enzyme #1 causes phenylalanine to build up. b. A mutation for enzyme $\# 2$ prevents tyrosine from being synthesized. c. A mutation at enzyme #3 prevents homogentistate from being synthesized. d. A mutation for enzyme $\# 2$ could hide a mutation in enzyme $=4$ e. Each step in a pathway such as this is catalyzed by an enzyme, which is coded by a gene.

Which statement about the following pathway is false?
a. A mutation for enzyme #1 causes phenylalanine to build up.
b. A mutation for enzyme $\# 2$ prevents tyrosine from being synthesized.
c. A mutation at enzyme #3 prevents homogentistate from being synthesized.
d. A mutation for enzyme $\# 2$ could hide a mutation in enzyme $=4$
e. Each step in a pathway such as this is catalyzed by an enzyme, which is coded by a gene.

Key Concepts

Genetic Mutations in Enzymes

Genetic mutations in the genes coding for enzymes can lead to altered enzyme function or complete loss of catalytic activity. These mutations impact the efficiency of biochemical reactions in metabolic pathways, potentially causing buildup of substrates or inability to synthesize essential compounds.

Metabolic Pathways

Metabolic pathways are series of interconnected biochemical reactions where substrates are modified step-by-step by enzymes to produce final products. Each enzyme in the pathway catalyzes a specific reaction, and proper function is essential for the overall progression and balance of metabolic processes.

Enzyme Catalysis

Enzyme catalysis refers to the acceleration of chemical reactions by proteins that act as biological catalysts. In metabolic pathways, each enzymatic step is crucial, and disruptions caused by mutations can block substrate conversion, leading to the accumulation of intermediates or deficiency of downstream products.

Epistasis

Epistasis is the interaction where the effect of one gene (or mutation) masks or modifies the effect of another gene in the same pathway. In metabolic pathways, an early mutation can obscure the phenotypic effects of mutations occurring in enzymes that act later in the sequence, thereby influencing the observable outcome of genetic variations.

Transcript

00:01 Okay, for this question, we're looking at a pathway depicted in the textbook.

00:05 What statement about it is false.

00:07 Is it a, a mutation in enzyme 1 would cause phenylalanine to build up.

00:14 B, a mutation in enzyme 2 would keep tyrosine from being synthesized.

00:19 C, a mutation in enzyme 3 would prevent the homogenestate form from being synthesized.

00:27 D, a mutation in enzyme 2 could hide a mutation in enzyme 4, or e, each step is catalyzed by an enzyme, which is coded for biogen.

00:38 Okay, so the pathway is, it starts at phenylalanine, we'll call that p, then it goes to tyrosine, then it goes to an intermediate, then it goes to the homogenesate, and then finally it is broken down into.

00:57 Co2 plus h2, so i'll put an x there.

01:01 And tyrosine can also be turned into another product.

01:05 O, or other.

01:07 So we have kind of a complex pathway here.

01:11 Okay, let's look her statements.

01:13 First of all, let's look at e because that's an easy one.

01:16 Each step is catalyzed by an enzyme, what's coated for biogen? well, we can see that each step does have an enzyme attached to it.

01:22 Each of these arrows represents an enzymatically catalyzed process, and enzymes are proteins, so they are coded for biogen.

01:30 Okay.

01:32 Let's start.

01:33 A, if a mutation is in step one, we'll have phenylalanine builder.

01:37 So this is step one...