Plant Enzymes and Cell Types

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary role of nigari in the production of tofu?

Enhances the flavor of the soymilk

Helps coagulate hot soymilk (correct)

Improves the texture of tofu

Provides essential nutrients

Which protein is primarily responsible for muscle contraction?

Actin (correct)

Myoglobin

Collagen

Elastin

What compound is primarily responsible for the pungent flavor in Cruciferae vegetables?

Capsaicin

Allicin

Myrosinase

Sinigrin (correct)

What distinguishes prime cuts of meat from choice cuts?

Prime cuts have more marbling Signup and view all the answers

Which pigment is known for giving fruits and vegetables a blue or purple color?

Anthocyanin Signup and view all the answers

What is the structural unit of a muscle fiber called?

Sarcomere Signup and view all the answers

What role do flavonoids play in plants?

They are pigments that contribute to color. Signup and view all the answers

Which protein is primarily responsible for the tenderness of meat?

Collagen Signup and view all the answers

Which of the following compounds is a sulfur-containing compound found in garlic?

Allicin Signup and view all the answers

What pigment is responsible for the green color in vegetables?

Chlorophyll Signup and view all the answers

How does myoglobin affect the appearance of meat?

Changes its color Signup and view all the answers

Which type of carotenoid has value as a source of vitamin A?

Carotenes Signup and view all the answers

What effect does rigor mortis have on meat texture?

Increases toughness Signup and view all the answers

What is the function of connective tissue in muscle fibers?

Supports and binds muscle fibers Signup and view all the answers

What is the primary function of lectins found in legumes?

They bind to carbohydrates and eliminate toxins. Signup and view all the answers

Vacuoles in plant cells are notable for containing which group of compounds?

Polyphenols Signup and view all the answers

What is the effect of oxymyoglobin on meat color?

Promotes a red color when exposed to oxygen Signup and view all the answers

Which cooking method combines both dry and wet heat at a low temperature after browning?

Braising Signup and view all the answers

What color does nitric oxide myoglobin contribute to cured meats?

Pink Signup and view all the answers

What defines a crustacean?

Hard-shelled, aquatic animals Signup and view all the answers

Which of the following describes the dark muscle in fish?

It plays a role in sustained swimming. Signup and view all the answers

Which substance causes the pungent odor in fish?

Trimethylamine Signup and view all the answers

Which method uses lower temperatures to gently cook food in a liquid?

Poaching Signup and view all the answers

What type of emulsion involves more water than fat?

Oil in water emulsion Signup and view all the answers

What is the primary function of pectinase in fruit processing?

To break down pectin into shorter, more soluble chains Signup and view all the answers

How does pectin esterase contribute to the ripening of fruits?

It breaks down pectin into methanol and pectin acids Signup and view all the answers

What role does polyphenol oxidase play in fruits and vegetables?

It causes browning reactions when exposed to air Signup and view all the answers

Which type of plant cell is primarily involved in storage, photosynthesis, and tissue repair?

Parenchyma cells Signup and view all the answers

What characteristic distinguishes collenchyma cells from other plant cell types?

They are the toughest plant cells providing support Signup and view all the answers

What is the primary function of lignin in plant cells?

To strengthen the structure of the cell wall Signup and view all the answers

What is hemicellulose's role in plant cell walls?

It adds structural support and becomes soluble at higher pH Signup and view all the answers

What is turgor pressure and its significance in plant tissues?

It is the pressure exerted by the cell contents on the cell wall, contributing to firmness Signup and view all the answers

What is the role of an emulsifier in food preparation?

To help combine two immiscible liquids into a stable emulsion Signup and view all the answers

Which class of lipids acts as emulsifiers and has a hydrophilic head and hydrophobic tails?

Phospholipids Signup and view all the answers

What happens during the creaming of an emulsion?

Dispersed particles rise to the surface due to density differences Signup and view all the answers

What is lecithin derived from?

Egg yolks, soybeans, and sunflower Signup and view all the answers

What does the breaking of an emulsion result in?

The separation of the mixture into distinct layers Signup and view all the answers

Study Notes

Pectinases and Pectin Esterases

Pectinases are enzymes that break down pectin chains, making them more water-soluble. They are found in fruit cell walls.
Pectin esterases are enzymes that remove methyl ester groups from pectin, leading to a more soluble and less effective cementing agent.
Pectin esterases play a role in fruit ripening and gelling.

Polyphenol Oxidase

This enzyme causes browning in fruits and vegetables.

Plant Cells

Parenchyma cells are fundamental plant cells involved in storage, photosynthesis, and repair. They can be closely packed or loosely packed with airspaces.
Collenchyma cells are tougher plant cells, found in the peel of an apple for example.
Sclerenchyma cells are the hardest plant cells, containing lignin and providing structure. They give pears their gritty texture.

Lignin and Hemicellulose

Lignin strengthens cell walls and is a major component of plants. It is indigestible by humans and unaffected by heat.
Hemicellulose provides structural support in plant cell walls. It softens at higher pH.

Turgor Pressure and Plastids

Turgor pressure is the pressure exerted by the cell contents on the cell wall, contributing to plant tissue firmness.
Plastids are small organelles within the cell membrane, involved in storing starch, fat, pigments, and enzymes.

Polyphenols

Polyphenols are naturally occurring plant compounds found in fruits, vegetables, and beverages.
They are found in the vacuole of cells and are responsible for color, taste, and antioxidant properties.

Allicin, Allium, Cruciferae, and Sinigrin

Allicin is a sulfur-containing compound that gives garlic its smell and taste. It has antimicrobial properties.
Allium is a family of plants including onions, garlic, and chives.
Cruciferae is a family of plants including cabbage, cauliflower, Brussels sprouts, kale, and turnips. These plants often have strong flavors, especially when raw.
Sinigrin is a compound found in Cruciferae vegetables that gives them their pungent, sometimes bitter, flavor.

Mustard Oil and Capsaicin

Mustard oil is produced when the enzyme myrosinase breaks down sinigrin in mustard seeds.
Capsaicin is the compound responsible for the heat in chili peppers.

Flavonoids

Flavonoids are water-soluble pigments responsible for fruit and vegetable color.
Anthocyanin produces blue, red, pink, and purple colors.
Anthoxanthin produces yellow and white colors.

Chlorophyll and Carotenoids

Chlorophyll is a green pigment found in chloroplasts.
Carotenoids are fat-soluble pigments that produce orange, yellow, and red colors. They are divided into carotenes, which have vitamin A value, and xanthophylls, which have no vitamin A value.

Legumes

Legumes are dried beans and peas.
Lectins are proteins found in legumes that bind to carbs, hemoglobin, coagulants, and eliminate toxic substances.
Trypsin inhibitors are enzymes that digest protein in legumes and eliminate toxic substances.

Tofu

Tofu is made by gelling hot soymilk with nigari, a magnesium chloride solution, or calcium sulfate.

Muscle Proteins

Actin is a muscle protein that is arranged in thin filaments.
Myosin is a muscle protein that is shaped like a golf club and forms thick filaments. Myosin interacts with actin to cause muscle contraction.

Muscle Structure

Fibrils are small, thread-like structures found in muscle fibers.
Sarcomeres are the basic contracting units of muscle fibers and are made up of myosin and actin.
Muscle fibers are bundles of fibrils.
Sarcolemma is the cell membrane that surrounds a muscle fiber.

Connective Tissue

Connective tissue is a gelatinous material with collagen and elastin fibers. This tissue surrounds bundles of muscle fibers and provides support, binding, and protection.

Collagen and Elastin

Collagen is a protein that is white in color, does not stretch easily, and is affected by cooking. It affects the texture of meat.
Elastin is a protein that stretches easily, is yellowish in color, and is not significantly affected by cooking.

Marbling of Meat

Marbling of meat refers to the white flecks of intramuscular fat distributed through muscle fibers. It contributes to tenderness, juiciness, and flavor.

Cuts of Meat

Prime cuts of meat have the most marbling and are considered the most flavorful and tender.
Choice cuts have less marbling than prime cuts.
Select cuts have the least marbling and are less flavorful and tender.

Rigor Mortis

Rigor mortis is a condition that occurs after death when actin and myosin form stable cross-links, making the meat tough.

Myoglobin and Meat Color

Myoglobin is a protein that contains iron and is responsible for the purplish-red color of meat.
Oxymyoglobin is a form of myoglobin that binds oxygen and gives meat a bright red color. This form is often promoted in vacuum-sealed meats.
Metmyoglobin is a form of myoglobin that has been oxidized and gives meat a brown color.
Nitric oxide myoglobin is a chemical compound formed when nitric oxide binds to myoglobin. It gives cured meats like bacon and ham a pink color.

Crustaceans and Mollusks

Crustaceans are animals with hard shells and multiple pairs of legs, often living in water.
Mollusks are soft-bodied invertebrates with shells but no backbones.

Fish Muscle

Lateral Muscle is one of the two main muscles in fin fish structure, making up a large portion of the meat.
Dark Muscle is the other main muscle in fin fish, also known as red muscle.

Cooking Methods

Braising is a moist heat cooking method that combines dry and wet heat. It usually involves browning the food at a high temperature, then simmering it in liquid at a lower temperature.
Roasting is a dry heat cooking method that involves cooking food evenly at a temperature above 300 degrees F.
Poaching is a cooking method that involves gently simmering food in liquid at a temperature below boiling.

Fish Odor

Trimethylamine is an organic compound that is responsible for the strong odor of fish. Bacteria convert trimethylamine oxide (TMAO) to trimethylamine.

Salmon Color

Canthaxanthin is a pigment added to feed farmed salmon to give their skin and egg yolks a red color.
Astaxanthin is a natural antioxidant and pigment that gives salmon its natural pink color.

Emulsions

Emulsion is a mixture of two or more liquids that are normally immiscible, but are combined into a stable consistency.
Oil-in-water emulsion has oil droplets dispersed in water. There is more water than fat.
Water-in-oil emulsion has water droplets dispersed in oil. There is more fat than water.

Emulsifiers

An emulsifier is a chemical additive that helps combine immiscible liquids into a stable emulsion. Examples include lecithin and carrageenan.
Phospholipids are a class of lipids that act as emulsifiers. They have a hydrophilic head and two hydrophobic tails.

Creaming and Breaking of Emulsions

Creaming occurs when the dispersed particles in an emulsion rise to the surface, often due to a density difference between the particles and the serum phase.
Breaking of an emulsion occurs when the mixture separates into distinct layers, due to the breakdown of the emulsifying agent.

Lecithin

Lecithin is a fatty substance derived from egg yolks, soybeans, sunflower, and canola that is used as an emulsifier.

Egg Structure

Vitelline membrane is a thin, transparent layer that surrounds the egg yolk.
Chalaza are the white robe-like strands that suspend the yolk in the center of the egg white.
Ovalbumin is the main protein in egg whites and is responsible for the egg white’s structure.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the roles of various plant enzymes such as pectinases and polyphenol oxidase, alongside the structural types of plant cells including parenchyma, collenchyma, and sclerenchyma. Understand how these components contribute to plant physiology and fruit ripening. Test your knowledge on the significance of lignin and hemicellulose in plant structure.