exam 1

GENETICS BASICS

Flashcard 1

Front (Q): What is a gene?
Back (A): A gene is a segment of DNA that codes for a specific trait (e.g., hair color).

Flashcard 2

Front (Q): What is an allele?
Back (A): An allele is a variant form of a gene. Each person inherits two alleles (one from each parent).

Flashcard 3

Front (Q): Define genotype vs. phenotype.
Back (A):

  • Genotype: The genetic makeup (the actual alleles) of an individual.

  • Phenotype: The observable, physical expression of those genes.

Flashcard 4

Front (Q): What do dominant and recessive alleles mean?
Back (A):

  • Dominant: Masks the expression of a recessive allele; represented by uppercase letters (e.g., A).

  • Recessive: Expressed only if no dominant allele is present; represented by lowercase letters (e.g., a).

Flashcard 5

Front (Q): Define homozygous and heterozygous.
Back (A):

  • Homozygous: Having two identical alleles (e.g., AA or aa).

  • Heterozygous: Having two different alleles (e.g., Aa).

Flashcard 6

Front (Q): What is the difference between diploid (2N) and haploid (1N) cells?
Back (A):

  • Diploid (2N) cells have 23 pairs of chromosomes (46 total).

  • Haploid (1N) cells (gametes) have 23 total chromosomes.

Flashcard 7

Front (Q): Why does the male determine the sex of a child in humans?
Back (A):
Males have X and Y chromosomes (XY). During meiosis, they produce sperm with either an X or a Y. Females only produce X gametes (XX).

MODES OF INHERITANCE

Flashcard 8

Front (Q): In dominant/recessive inheritance, how do heterozygotes look?
Back (A):
In a heterozygote (Aa), the dominant allele determines the phenotype. The recessive allele is “hidden.”

Flashcard 9

Front (Q): Give an example of a dominant/recessive trait from the lab text.
Back (A):

  • Albinism (m) is recessive.

  • Normal pigmentation (M) is dominant.

Flashcard 10

Front (Q): What is Cystic Fibrosis (as described in the text)?
Back (A):
A recessive genetic disorder where a faulty chloride channel leads to thick, sticky mucus in the pancreas, lungs, etc.

Flashcard 11

Front (Q): Describe sex-linked (X-linked) inheritance.
Back (A):
Traits on the X chromosome. Males (XY) have only one X, so a recessive allele on X will be fully expressed. Females (XX) need two copies of the recessive allele to show the trait.

Flashcard 12

Front (Q): What are two common X-linked recessive conditions mentioned?
Back (A):

  • Color blindness

  • Hemophilia

Flashcard 13

Front (Q): In ABO blood groups, why are A and B called codominant?
Back (A):
Because if A and B alleles are both present (AB), they are equally expressed on red blood cells (both A and B antigens appear).

Flashcard 14

Front (Q): Which ABO genotype(s) result in Type O blood?
Back (A):
Type O can only be OO (both alleles are O).

OBSERVABLE TRAITS (PHENOTYPES)

Flashcard 15

Front (Q): Which allele is dominant for earlobes?
Back (A):
Free-hanging earlobes (E) is dominant; attached earlobes (e) is recessive.

Flashcard 16

Front (Q): What is a widow’s peak and which allele is dominant?
Back (A):
A widow’s peak (W) is a distinct downward hairline in the center of the forehead. W is dominant, w is recessive.

Flashcard 17

Front (Q): How can you tell if you have the long palmar muscle?
Back (A):
Clench your fist and flex your hand. If you feel 3 tendons in the wrist, you have the recessive “long palmar muscle” allele (l).

Flashcard 18

Front (Q): Which genotype leads to blue eyes in the simplified model given?
Back (A):
Blue eyes occur when a person is homozygous recessive (pp) and thus lacks pigment in the front of the iris.

Flashcard 19

Front (Q): How do you test for PTC tasting?
Back (A):
Place a PTC-impregnated strip on your tongue. If it tastes bitter, you have at least one dominant T allele. If it’s tasteless, you are tt.

METRIFICATION & MEASUREMENTS

Flashcard 20

Front (Q): What are the basic metric units for length, volume, and mass?
Back (A):

  • Meter (m) for length

  • Liter (L) for volume

  • Gram (g) for mass

Flashcard 21

Front (Q): Give the metric prefixes for 1000, 1/100, and 1/1000.
Back (A):

  • kilo- (k) = 1000

  • centi- (c) = 1/100

  • milli- (m) = 1/1000

Flashcard 22

Front (Q): How do you convert 242 milligrams (mg) to grams (g)?
Back (A):
1 g = 1000 mg, so 242 mg = 0.242 g (move the decimal three places to the left).

Flashcard 23

Front (Q): What are 0 °C and 100 °C on the Celsius scale?
Back (A):

  • 0 °C = freezing point of water

  • 100 °C = boiling point of water

Flashcard 24

Front (Q): How do you express ratios and proportions?
Back (A):

  • Ratio: compares two quantities (e.g., 1:4 or 1/4).

  • Proportion: sets two ratios equal (A/B = C/D). If three values are known, the fourth can be found.

Flashcard 25

Front (Q): Example: If paper moves at 25 mm/sec on an ECG, and one heartbeat cycle measures 15 mm, what is the heart rate in beats/min?
Back (A):

  • Time per beat = 15 mm ÷ 25 mm/s = 0.6 s/beat

  • Beats per minute = 60 s ÷ 0.6 s = 100 beats/min