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.
4
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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