Lecture 11 Flashcards by Alysa Freeman

What is DNA?

DNA is a collection of genes.

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What are chromosomes?

Chromosomes are sections of DNA that contain dozens to hundreds of genes.

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What is the function of a gene?

A gene is a recipe or code for making a specific protein.

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What happens when a certain protein needs to be made?

The corresponding gene is transcribed to make a copy, or mRNA.

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What are the properties of DNA?

It can replicate itself
It can store information
It can direct synthesis of proteins
It can mutate

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How is DNA organized to prevent tangling?

DNA is double-stranded and wrapped around histones.

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What is the structure of DNA?

DNA is organized in a double helix structure.

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How many chromosomes are there in human DNA?

There are 46 chromosomes in human DNA.

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What is the process of DNA replication?

DNA replication is the process of copying all the cell’s genes to duplicate the entire DNA library.

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What is a centromere?

The centromere is the central part of the chromosome that contains many valuable genes.

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What are telomeres?

Telomeres are the end tips of chromosomes that protect important genetic information.

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What happens to telomeres during cell division?

Telomeres get shorter with each cell division.

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What role does telomerase play in cells?

Telomerase keeps the telomeres at their original length.

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What are stem cells?

Stem cells are good undifferentiated cells that can divide indefinitely and differentiate into any type of cell.

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What are cancer cells?

Cancer cells are bad undifferentiated cells that have lost their ability to differentiate and express telomerase.

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What is the cell cycle?

The cell cycle is the process that describes how cells replicate and divide.

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What are the three reasons for cell division?

For growth
To replace old cells
To heal damaged tissues

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What are the two stages of the M-phase of the cell cycle?

Mitosis
Cytokinesis

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What occurs during mitosis?

Mitosis is the division of one nucleus into two nuclei.

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What are the four phases of mitosis?

Prophase
Metaphase
Anaphase
Telophase

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What is the epidermis?

The epidermis is the top layer of skin made of stratified squamous epithelium.

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What is the function of the dermis?

The dermis is the metabolically active layer of skin containing blood vessels, nerve endings, and glands.

What is the hypodermis?

The hypodermis is the layer of connective tissue under the dermis that connects skin to underlying muscle.

Fill in the blank: The top layer of the epidermis is called the _______.

Stratum Corneum

What is keratin?

Keratin is a waterproof protein found in the top layer of the epidermis.

What is the hair shaft?

The hair shaft is the part of the hair above the skin surface.

What is the hair root?

The hair root is the part of the hair below the skin surface.

What is the role of sebaceous glands?

Sebaceous glands drain oil into hair follicles to moisturize the hair.

What is the purpose of sweat glands?

Sweat glands help regulate body temperature and excrete waste.

What is the hypodermis composed of?

Areolar or adipose connective tissue ## Footnote It connects the skin to the underlying muscle.

What is the part of the hair above the skin surface called?

Hair shaft

What is the function of the arrector pili muscle?

To pull the hair into an upright position

What is the top layer of the skin’s epidermis called?

Stratum corneum ## Footnote Is composed of dead epithelial cells

Which protein fills the cells in the stratum corneum?

Keratin

What is the primary function of keratin in the skin?

Water-proofing the skin

How does the skin regulate body temperature when it gets too hot?

Blood vessels dilate and sweating begins

What happens to blood vessels in the skin when it gets cold?

They constrict to keep blood closer to the core

What are the different types of sensory receptors found in the skin?

* Pressure receptors * Thermoreceptors * Pain receptors

What is produced in the skin in the presence of UV light?

Cholecalciferol from 7-dehydrocholesterol

What is a secondary function of the skin?

Excretion of electrolytes

True or False: Water-soluble molecules can easily pass through the skin.

False

What are decubitus ulcers commonly known as?

Pressure sores or bed sores

What causes decubitus ulcers?

Prolonged pressure that cuts off circulation ## Footnote Tissue necrosis leads to tissue disintegration and sores

Which stage of decubitus ulcer is indicated when white bone can be seen at the bottom?

Stage IV

What is the key difference between the stages of decubitus ulcers and degrees of burns?

Stages of decubitus ulcers are based on tissue layers affected; degrees of burns are based on skin depth affected.

What is an example of a first-degree burn?

Superficial burn, such as a sunburn

Events of Prophase

1. Centrioles replicate and create two opposite poles 2. Spindle fibers pull the nuclear membrane apart and attach directly to the chromosomes

Events of Metaphase

1. Spindle fibers keep pulling on the exposed chromosomes. 2. As the spindle fibers pull with equal force toward opposite poles, the chromosomes align on the Equatorial Plane.

Events of Anaphase

1. The centromeres of all the chromosomes replicate, causing the chromosomes to split in half. 2. As the spindle fibers keep pulling, they force the separated daughter chromosomes to gather at opposite poles of the cell.

Events of Telophase

1. Spindle fibers disappear. 2. Nuclear membrane re-forms around each set of daughter chromosomes at opposite poles of the cell. The result is a cell with 2 nuclei, ready for cytokinesis.

Cytokinesis

Follows Telophase. During cytokinesis, the cytoplasmic membrane begins pinching on opposites sides in order to separate the 2 nuclei. The “pinching” continues until the membrane separates the 2 nuclei from each other completely into 2 new daughter cells.

Which of the following is NOT a function of skin? a. Collection of sensory information b. Protection from microbes c. Production of Vitamin D d. Regulation of body temperature e. Absorption of water

e. Absorption of water

Which of the following is NOT found in the Dermis? a. Hair root b. Arrector pili muscle c. Sebaceous glands d. Sweat glands e. Keratin

e. Keratin ## Footnote Keratin is a protein found in the outermost layer of the skin (epidermis)

Functions of the skin

1. Protection of the organism from microbes and dehydration 2. Regulation of body temperature 3. Collection of Sensory Information 4. Production of Vitamin D 5. Excretion of Electrolytes: this is a secondary function of skin 6. Absorption of Some Fat-Soluble Substances