Biology Kaplan Book

Question 1

viroids

Answer 1

small pathogens consisting of a very short circular single-stranded RNA that infect plants

brings large number of RNA sequences and silences genes in plant genome

Question 2

prions

Answer 2

infectious proteins

cause disease by triggering misfolding of other proteins

Question 3

positive sense RNA viruses

Answer 3

genome may be directly translated to functional proteins by the ribosomes of host cell, like mRNA

Question 4

Negative sense RNA viruses

Answer 4

require synthesis of an RNA strand complementary to the negative-sense strand, which can then be used as a template for protein synthesis

must carry an RNA replicase in virion to ensure synthesis

Question 5

extrusion

Answer 5

the process in which a virus leaves the cell by fusing with the plasma membrane, allowing the survival of the host cell and continued use of host cell by virus
- a productive cycle

Question 6

p53

Answer 6

the main protein in control of stopping the cell cycle (going into arrest at the checkpoints) until the DNA has been repaired if damaged

damage/mutation to the gene that produces p53 can lead to cancer

Question 7

what molecules are responsible for the cell cycle?

Answer 7

cyclins and cyclin-dependent kinases (CDK)

CDK must be activated by the right cyclins

Question 8

synaptonemal complex

Answer 8

a group of proteins that holds homologous chromosomes together

Question 9

Mendel’s second law (of independent assortment)

Answer 9

states that the inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes

Question 10

Mendel’s first law (of segregation)

Answer 10

the distribution of homologous chromosomes to the two intermediate daughter cells is random with respect to parental origin

Question 11

What is the pathway of sperm through the male reproductive system?

Answer 11

SEVE(N) UP

```
Seminiferous tubules
Epididymis
Vas deferens
Ejactulatory duct
Nothing
Urethra
Penis
~~~

Question 12

deuterostomes

Answer 12

develops into anus from blastopore

“deu” = 2 = “number two” = doo doo

Question 13

protostomes

Answer 13

develops into mouth from blastopore

Question 14

ectoderm

Answer 14

“attracto”derm (things that attracts us to others, such as cosmetic features and “smarts”)

outer layer of germ layers; gives rise to the integument (epidermis, hair, nails, and epithelia of nose, mouth, and lower anal canal), the lens of the eye, nervous system (w/ adrenal medulla) and inner ear

Question 15

mesoderm

Answer 15

“means”oderm = means of getting around as an organism, such as bones and muscle; means of getting around in the body, such as the circulatory system; means of “getting around” wink wink (such as gonads)

middle layer; develops into several different systems including musculoskeletal, circulatory, and most of the excretory systems; also gives rise to gonads and muscular/connective tissue layers of digestive and respiratory systems and adrenal cortex

Question 16

endoderm

Answer 16

linings of “endernal” (internal) organs

• the digestive and respiratory tract, including lungs, and accessory organs attached to these systems
• pancreas, thyroid, bladder, and distal urinary tracts, as well as parts of liver

Question 17

What happens after penetration of the sperm through the cell membrane of the secondary oocyte (the cortical reaction)?

Answer 17

Calcium ions are released, depolarizing the membrane of ovum, serving 2 purposes:

1. depolarization prevents fertilization by multiple sperm cells
2. increased Ca2+ concentration increases the metabolic rate of the newly formed diploid zygote

Question 18

what tissues do the neural crest cells develop into?

Answer 18

the PNS

Question 19

what does it mean for a cell to be determined?

Answer 19

it is committed to a particular cell lineage, but not yet actually produced the products it needs to carry out the functions of that cell type

Question 20

what does it mean for a cell to differentiate?

Answer 20

it assumes the structure, function, and biochemistry of that cell type. Goal is to produce products it needs to carry out the function of that cell type

Question 21

what determines how many different cell types a stem cell can become?

Answer 21

potency

Question 22

explain the different types of potency

Answer 22

totipotent: ultimately can differentiate into any cell type (either in fetus or in placental structures); has greatest potency
pluripotent: cells can differentiate into any cell type except for those found in placental structures (differentiate into the three germ cell layers ecto, meso, endo)
multipotent: can differentiate into multiple types of cells within a particular group (like how hematopoietic stem cells can differentiate into all cells only found in blood like WBC, RBC, platelets)

Question 23

what molecules cause determination of cells

Answer 23

morphogens

examples: transforming growth factor beta (TGF-B), sonic hedgehog (Shh), and epidermal growth factor (EGF)

Question 24

Where does oxygenation occur in fetal circulation?

Answer 24

at the placenta

Question 25

describe the direction which the umbilical arteries take

Answer 25

carries blood AWAY from the fetus toward the placenta

Question 26

describe the direction which the umbilical vein take to carry blood

Answer 26

carries blood towards the fetus from the placenta; carries oxygenated blood

Question 27

what are the three shunts constructed by the fetus to actively direct. What are their functions?

Answer 27

1. foramen ovale: one-way valve connecting R atrium to L atrium, instead of the R ventricle, thereby pumped through aorta into systemic circulation directly (bypass lungs)
2. ductus arteriousus: leftover blood from pulmonary artery to aorta to systemic circulation (bypass lungs)
3. ductus venosus: shunts blood returning from placenta via umbilical vein directly to inferior vena cava; (bypass liver, but still receive some blood supply)

Question 28

mnemonic for estrogen and progesterone

Answer 28

EStrogen EStablishes and PROgesterone PROtects the endometrium

Question 29

What is the general rule for length of gestation and number of offsprings

Answer 29

the LARGER the animal, the LONGER the gestational period, the FEWER the offspring per pregnancy

Question 30

What are key developmental features of the first trimester?

Answer 30

basic organ, bone formation => fetus

Question 31

what are key developmental features of the second trimester

Answer 31

tremendous amount of growth + movement; human face and fingers/toes elongation

Question 32

what are key developmental features of the third trimester

Answer 32

rapid growth + brain development, antibodies transported to fetus in preparation for outside world

growth rate and movement decrease on 9th month

Question 33

what coordinates the rhythmic contractions of the uterine smooth muscle during vaginal childbirth?

Answer 33

prostaglandins and oxytocin