exam 2

Question 1

What are characteristics of a good model organism?

Answer 1

short generation time, many offspring, easy to maintain, small, easy to arrange matings, easily recognizable traits, inexpensive to care for

Question 2

Monohybrid Cross

Answer 2

mating between individuals that are heterozygous for a single trait (AaxAa)

Question 3

Dihybrid Cross

Answer 3

mating between two individuals that are heterozygous for two traits (PpxSs) → PS,Ps,pS,ps

Question 4

chromosome theory of inheritance

Answer 4

chromosomes are composed of Mendel’s hereditary determinants, or what we know now as genes

Question 5

Mendel’s Principle of Segregation

Answer 5

genes must segregate equally into gametes such that offspring have an equal likelihood of inheriting either factor

Question 6

Mendel’s Law of Dominance

Answer 6

in a heterozygote one trait will conceal the presence of another trait for the same characteristic

Question 7

Mendel’s Principle of Independent Assortment

Answer 7

genes do not influence each other with regard to the sorting of alleles into gametes and every possible combination of alleles for every gene is equally likely to occurs

Question 8

What is a autosomal trait?

Answer 8

a way a genetic trait or condition can be passed down from parent to child. one copy of a mutated gene from one isn’t can cause the genetic condition, a child who has a parents with the mutated gene has 50% chances is inheriting that mutated gene

Question 9

how to tell if a trait is autosomal or sex-linked?

Answer 9

if a trait appears equally often in males & females, it is likely to be autosomal. if males are more likely to have the trait, it is usually x-linked.

Question 10

What is a sex-linked trait?

Answer 10

when a gene being examined is present on the X, but not the Y chromosome it is X-linked

Question 11

incomplete dominance

Answer 11

one of the alleles appears in the phenotype in the heterozygote but not to the exclusion of the other one which can also be seen

Question 12

codominance

Answer 12

both alleles for the same characteristic are simultaneously expressed in the heterozygote think of A or B blood type

Question 13

epistasis

Answer 13

an interacting between genes such that one gene makes it interferes with the expression of another

Question 14

polygenic traits

Answer 14

a characteristic, such as height or skin color, that is influenced by two or more genes. since multiple genes are involved polygenic trait do not follow Mendelian inheritance

Question 15

how can genes be affected

Answer 15

genes can be affected by the physical environment as well as the genetic environment

Question 16

what are the two category of cells in the nervous system

Answer 16

neurons and gila

Question 17

DNA Replication

Answer 17

each of the two strands that make up the double helix serve as a template from which the new strands are copied, the new strand will be complementary to the parental strand

Question 18

Gel Electrophoresis

Answer 18

a technique used to separate charged molecules based on size and charge, nucleic acids can be separated as whole chromosome or as fragments. loaded into a slot at one end of the gel matrix and an electric current is applied to the gel, which causes the negatively charged molecules to be pulled toward the end with the positively charged electrode.

Question 19

Polymerase Chain Reaction (PCR)

Answer 19

used to rapidly increase the number of copies of specific regions of DNA for further analyses

Question 20

what does a PCR contain?

Answer 20

sample of double-stranded DNA, two artificially synthesized primers, four dNTPs, DNA polymerase that can tolerate high temperatures, salts, and pH buffer

Question 21

PCR Amplification

Answer 21

denature: DNA strands are denatured through heating; anneal: the reaction is cooled to allow primers to anneal to template strands; extend: the reaction is warmed so DNA polymerase catalyzes new strands

Question 22

What are some uses of PCR?

Answer 22

paternity analysis, identification of the owner of a DNA sample left at a crime scene, comparison of small amounts of ancient DNA with modern organisms, determining the sequence of nucleotides in a specific region

Question 23

neurons

Answer 23

excitable, can generate and transmit electrical signals called action potentials

Question 24

gila or gilal cells

Answer 24

provide support and maintain the extracellular environment

Question 25

stimulus

Answer 25

any factor that causes a nerve signal to be generated. alters the permeability of a portion of the membrane and allows ions to pass through, and changed the membrane’s voltage

Question 26

action potential

Answer 26

a change in the membrane voltage, from resting potential, to the maximum level, and then back to the resting potential

Question 27

synapses

Answer 27

junctions where signals are transmitted between two neurons or between neutrons and effector cells

Question 28

sensory receptors

Answer 28

specialized cells or neurons that are tuned to the conditions of the external world and the internal organs.

Question 29

how do sensory receptors work?

Answer 29

trigger an action potential to send information to the central nervous system. sensation depends on the part of the brain that receives the action potential

Question 30

chemoreceptors

Answer 30

receptor proteins that bind to specific molecules, their ligands are responsible for taste and smell. can also monitor the internal environment such as CO2 levels in blood.

Question 31

mechanoreceptors

Answer 31

sensory cells that respond to physical (mechanical) forces. when the cell membrane is disturbed, cation channels open.

Question 32

electromagnetic receptors

Answer 32

responds to electricity, magnetism, and light

Question 33

rod cells

Answer 33

highly light sensitive and perceive shades of gray in dim light

Question 34

cone cells

Answer 34

functions at high levels; responsible for high-acuity color vision

Question 35

How do cone cells work in humans?

Answer 35

humans have three types of cone cells with slightly different open molecules which allows them to absorb different wavelengths of light

Question 36

what is nearsightedness?

Answer 36

inability to focus on distant objects, usually cause by an eyeball that is too long

Question 37

what is farsightedness?

Answer 37

inability to focus on close objects, usually caused by an eyeball that is too short

Question 38

what is an astigmatism?

Answer 38

blurred vision caused by a misshapen lens or cornea