Single-Base Substitutions Are Not Always A Problem Because They

A gene contains the sequence GGCTAAC. What is the sequence of the mRNA transcribed from this strand of DNA?

CCGAUUG

A small segment of DNA is used as a template for transcription. This DNA contains the base sequence CGT. If an mRNA transcript is made from the DNA that includes this sequence, what would be the anticodon on the tRNA that would bind to this corresponding mRNA

CGU FEEDBACK: A DNA triplet of CGT in the template strand would yield an mRNA codon of GCA. Therefore, the complementary tRNA anticodon would be CGU.

A triplet base sequence on the template strand of DNA reads ATT. What will be the corresponding mRNA codon, tRNA anticodon, and amino acid coded for by this DNA?

UAA; AUU; no amino acid (= stop codon)

Breaking down the mRNA produced from a particular gene will

down-regulate the gene.

Compare and contrast the genetic code in plants and humans.

The genetic code is identical for both plants and humans.

Genes code for which of these biological molecules?

Proteins

If you remove the terminator from a gene, how will this disrupt the function of RNA polymerase?

Transcription will not stop

In a ribosome in the process of translating a molecule of mRNA, a maximum of _________ tRNA molecules can be bound to the mRNA at any one time.

2 FEEDBACK Because there are two attachment sites on the ribosome, two tRNA molecules may be present at any one time.

In eukaryotes, the initial RNA product is processed to remove

introns

Refer to the information on the genetic code. Use this information to determine how many amino acids are coded for by the mRNA sequence AUGCGCAGUCGGUAG.

Single-base substitutions are not always a problem because they

do not cause a genetic "frameshift.

The process of gene transcription begins with the

binding of RNA polymerase to a region of DNA called the "promoter."

The synthesis of RNA molecules from a DNA template is known as

transcription. FEEDBACK: This is the definition of transcription, which is the first step in gene expression. Translation is the second step, and involves the creation of proteins from RNA transcripts.

To use the information contained in a gene to produce a functioning protein,

information must be transcribed into mRNA and then translated into amino acids.

The sequence ACCAGU could be in this animation TRANSCRIPTION VIDEO

an mRNA sequence.

Gene expression

the process by which genes are transcribed into RNA and then translated to make proteins

Transcription

synthesis of an RNA molecule from a DNA template(1 step in gene expression)

RNA polymerase

An enzyme that recognizes and binds a gene's promoter sequence and then separates the two strands of DNA during transcription

Intron

A stretch of DNA that does not code for anything

Messenger RNA - (mRNA)

A type of RNA that is complementary to a DNA template strand

Exons

A stretch of DNA that carries instructions for building a protein

Ribosomes

The site of protein synthesis (translation) in the cytoplasm. Ribosomes are embedded in the rough endoplasmic reticulum

Translation

The process by which ribosomes convert the information in mRNA into proteins

Codon

A unique sequence of 3 mRNA bases that either speciﬁes a particular amino acid during translation or signals the ribosomes where to start or stop translation.

Transfer RNA (tRNA)

A type of RNA that facilitates translation by delivering speciﬁc amino acids to the ribosomes as codons are read off of an mRNA.

Anticodon

A unique sequence of three nitrogenous bases at one end of a tRNA molecule that binds to the corresponding codon on an mRNA molecule

Ribosomal RNA -(rRNA)

A type of RNA that is an important component of ribosomes.

RNA splicing,

The removal of introns and joining of exons in eukaryotic RNA, forming an mRNA molecule with a continuous coding sequence; occurs before mRNA leaves the nucleus.

In which of the step(s) illustrated here does DNA replication occur?

Replication: steps 4 and 5.

In which step(s) does gene expression occur?

Expression: step 6.

Why is only one strand of DNA used as a template?

Because the other strand would code for the opposite mRNA.

Where is the mRNA destined to go once it has been transported out of the nucleus

Into the cytoplasm.

Which amino acid always begins an amino acid chain?

Methionine always begins the chain

Which codon and anticodon are associated with that amino acid?

The associated codon and anticodon are AUG and UAC, respectively.

Which mechanisms in a cell prevent mutations?

Checkpoints in the cell cycle prevent

Why is an insertion or a deletion in a gene more likely to alter the protein product than a substitution, such as A for C, would?

Because an insertion or deletion causes a "frameshift," so every single amino acid from that point on is likely to be different, as opposed to a substitution, where, at most, one amino acid changes.

At what control point is transcription regulated?

Control point 2

What is a possible advantage of regulating gene expression before transcription, versus after?

The cell does not waste time and energy producing mRNA transcripts that it will not use

A major difference between eggs and sperm is that

males produce many more sperm than females produce eggs

Among members of kingdom Animalia, external fertilization is commonly observed in

aquatic animals

A positive feedback loop

amplifies the output of a process until an endpoint is reached

Fertilization in humans occurs in which of the following structures?

Oviduct

In the natural world, animals may reproduce by

either asexual or sexual reproduction, depending on the animal

regulate(s) events in reproduction, growth, and development.

Hormones

The fallopian tube connects the

ovary and uterus

Tissues are

composed of integrated cells that perform a common function

Which organ system works with the respiratory system to deliver gases and the endocrine system to deliver hormones?

Circulatory system

Which of the following are hormones that are produced in abundance in males?

Androgens

Which of the following cells generated during spermatogenesis is the first haploid cell?

Secondary spermatocyte

Which of the following is a type of organ system?

Skeletal

Which of the following is correct about sperm cells?

They transmit paternal chromosomes to the zygote, but little other cellular machinery.

Which of the following is the last event in childbirth?

The umbilical cord and placenta are expelled

Which of the following parts of the body includes all of the others listed?

Organ system

Tissue

made up of cells that act in an integrated manner to perform a common set of functions

Organ

A collection of different types of tissues that form a functional unit with a distinctive shape and location in the body

Organ system

composed of two or more organs that work in a closely coordinated manner to perform a distinct set of functions in the body

Homeostasis

the process of maintaining a relatively constant internal state despite changes in the external environment

Negative feedback

The steps of a process that decrease its output

Zygote

The single cell that results from fertilization

Oogenesis

The series of cell divisions in human females that results in an egg.(egg production)

Spermatogenesis

The series of cell divisions in human males that results in sperm

Oviduct

Also called fallopian tube. The tube through which an egg travels from the ovary to the uterus

Ovary

Either of a pair of female reproductive organs that produce eggs and estrogens in vertebrates

Uterus

womb. The female reproductive organ in which a fertilized egg implants and develops until birth.

Anatomy

The study of body structure

physiology

the study of how the body and its parts work or function

4 types of tissue

epithelial, connective, muscle, nervous

homeostatic pathways

sequences of steps that reestablish homeostasis if there is any departure from the genetically determined normal state (also called the set point

11 major organ systems of the human body

circulatory, digestive, endocrine, excretory, immune, integumentary, muscular, nervous, reproductive, respiratory, skeletal

Sexual reproduction requires the production of haploid gametes

Oogenesis produces haploid eggs (ova), and spermatogenesis produces haploid sperm.

How many eggs are produced from each precursor cell?How many sperm?

1 egg/ 4 sperm

When estradiol levels reach a certain threshold, they trigger the release

luteinizing hormone (LH) from the pituitary, which triggers ovulation.

Which hormone is involved in producing the uterine lining?

Progesterone

Testes and ovaries produce three major types of hormones:

estrogens, progestogens, and androgens.

What is the role of estradiol in childbirth

High estradiol levels cause muscles in the uterus to become sensitive to oxytocin

Absorption is the

uptake of nutrients from the digestive tract.

A grandmother tells her grandchildren to eat lots of carrots if they want good eyesight. Although she might not know why this works, she is right because carrots contain carotene, a precursor to ___________, which is used to produce visual pigments.

vitamin A

Bile is produced in the ___________ and secreted into the small intestine by the ___________.

liver, gallbladder

Dietary fiber from foods such as oatmeal, brown rice, and popcorn are beneficial because they

influence the absorption of nutrients in the gut

In the human digestive system, chemical digestion of protein begins in the

stomach

In what way is the structure of the small intestine related to its function?

Finger-like villi increase the surface area available for absorption.

Skin contains all of the following EXCEPT

osteocytes.

The British Royal Navy used to give sailors lime juice to prevent scurvy. The key nutrient in limes that prevents scurvy is

vitamin C.

The extracellular matrix of cartilage is primarily made of

collagen

The first enzymes that food encounters in our body are in our

mouth

When you eat an apple, your body breaks down the tissues of the apple and absorbs the nutrients. What is the correct path, from first to last, an apple would take through your digestive system?

Mouth, stomach, small intestine, large intestine

Which of the following is present in a muscle sarcomere?

Actin and myosin filaments

Which of the following structures functions to lubricate joints?

Synovial sac

Which of the following vitamins would be most easily excreted if you ingested them in excess?

Vitamin C
FEEDBACK: Water-soluble vitamins (C and the B vitamins) are more easily excreted than fat-soluble vitamins (A, D, E, and K).

Which type of muscle do you contract voluntarily?

Skeletal

Vitamins

Any of various small, organic nutrients needed by the human body, but only in tiny amounts.

Nutrients

A chemical element that is required by a living organism

Essential amino acids

Any of the eight amino acids that can be obtained only from food

Minerals

Any of various small, inorganic nutrients needed by the human body for critical biological function, but only in small amounts

oral cavity

mouth

saliva

a fluid secreted into the oral cavity to aid in the digestion of food

phaynx

Also called throat. An area where the back of the mouth and the two nasal cavities join together into a single passageway

stomach

the organ of the digestion sytem, located between the esophagus and intestines in which most digestion occurs through mechanical and chemical means

Pancreas

A gland that produces insulin and secretes ﬂuids that aid in the digestion of food

liver

A large organ of the digestive system that produces bile, stores glycogen, and detoxiﬁes dangerous chemicals in the body

Gallbladder

An organ of the digestive system that stores bile made by the liver and dispenses the bile into the small intestine as needed

Axial skeleton

The part of the skeleton that supports and protects the long axis of the body. It includes the skull, the ribs, and a long, bony spinal column.

Appendicular skeleton

The part of the skeleton that has to do with motion. It is made up of the arms, legs, and pelvis

marrow

A tissue found in the cavities of hollow bones that, depending on the type of bone, stores fat or produces blood cells.

Ligaments

A specialized, ﬂexible band of tissue that joins bone to bone

Tendons

A specialized, ﬂexible band of tissue, rich in collagen, that joins muscle to bone.

skeletal muscle

A muscle that is attached to the bones of the skeleton and provides the force that moves the bones.

cardiac muscle

Involuntary muscle tissue found only in the heart.It has a banded appearance and branched muscle ﬁbers, and its contractions are entirely involuntary

smooth muscle

The specialized muscle found in the walls of the digestive system and blood vessels. It has no visible bands and its contractions are entirely involuntary

Actin filament

One of the two kinds of protein ﬁlaments, made of the protein actin, that is found in sarcomeres

myosin filaments

One of the two kinds of protein ﬁlaments, made of the protein myosin, that is found in sarcomeres.

Which vitamins described in the ﬁgure are important for healthy bones

Vitamins A, B12, C, and D.

Which vitamins are you more likely to overaccumulate?

The fat-soluble vitamins: A, D, E, and K.

What part of the digestive system hosts bacteria that produce vitamins?

The large intestine.

What is the shared function of the liver and gallbladder?

They produce, store, and release bile to digest fats.

In what way are the epithelial cells lining the villi modiﬁed to increase absorption?

The microvilli of the cells increase surface area even further.

Explain the role of the capillaries within each villus

The capillaries are important for moving nutrients from the villi and out to the rest of the body

What organs of the digestive system are involved in processing vitamin D?

The liver and kidneys.

How is skeletal muscle attached to bones in the skeleton?

tendon

List muscle structures from smallest to largest, beginning with sarcomeres.

Sarcomere, myoﬁbril, muscle ﬁber, muscle ﬁber bundle, muscle.

What are the components of the sarcomere?

Myosin, actin, Z disc

integumentary system

largest organ system in the human body, covering and protecting the surface of the body. It consists of skin and the structures embedded in the skin, such as hair and nails

Air leaving the lungs has

a lower concentration of oxygen and a higher concentration of carbon dioxide than outside air.

A low platelet count would most likely affect

blood clotting.

Gas exchange in the lungs is speeded up by

thin alveolar walls

Humans have a well-developed internal transport system, called the cardiovascular system, because

we have trillions of cells and an extensive network of vessels is needed to carry blood close to all body cells

In the human body, the highest blood pressure is recorded in

arteries near the heart

The area of the brain that processes and directs incoming sensory information is known as the

thalamus

The entire functional unit of a kidney is called a

nephron

The receptors that receive information concerning touch, hearing, and body position are called

mechanoreceptors.

The respiratory system can be divided into upper and lower portions. Which activity is accomplished in the lower portion?

An exchange of carbon dioxide and oxygen occurs between inhaled air and the blood

The signal for ventricular contraction arrives at the AV node earlier than the contraction begins. Why might the AV node intentionally delay transmitting the signal to the muscles of the ventricles?

To provide the time needed for the blood in the atria to flow into the ventricles

What best explains the purpose of the valves found in the veins?

Valves prevent the blood from reversing direction within veins when pressures are low, keeping blood flowing toward the heart.

When we inhale, air moves in through the mouth or nose and next moves into the

pharynx

Which of the following parts of a neuron is responsible for transmitting a signal to another cell

Axon

Which of the heart chambers indicated is responsible for pumping blood to the lungs?

The right ventricle pumps blood to the lungs through the pulmonary circuit. The left ventricle pumps blood out to the body through the systemic circuit. The right atrium receives blood returning from the body and the left atrium receives blood returning from the lungs.

Why do kidneys need to perform reabsorption?

Water and valuable solutes need to be returned to the bloodstream.

Plasma

Liquid part of blood

Red blood cells

Blood cells that carry oxygen from the lungs to the body cells.

Arteries

are large vessels (0.1-10 mm in diameter) that transport blood away from the heart

Veins

(0.1-2 mm) are large vessels that carry blood back to the heart

Capillaries

-(0.005- 0.01 mm)the smallest vessels, at, exchange materials by diffusion with nearby cells

Heart

a muscular organ the size of a ﬁst in humans that works as the body's circulatory pump

Systemic circuit

Circuit of blood that carries blood between the heart and the rest of the body.

Pulmonary circuit

carries blood to the lungs for gas exchange and returns it to the heart

Pharynx

throat

Larynx

voice box; passageway for air moving from pharynx to trachea; contains vocal cords

Trachea

another name for windpipes. Is the start of the lower respiratory system

Bronchioles

Smallest branches of the bronchi. Terminal bronchioles lead to alveolar ducts.

Alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood

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