unit 3 genetics and meiosis

Question 1

genotype

Answer 1

actual genetic makeup- letters are used

Question 2

phenotype

Answer 2

observed physical characteristics

Question 3

homozygous

Answer 3

both letters are the same- AA or aa

Question 4

heterozygous

Answer 4

different- Aa

Question 5

segregation

Answer 5

During gamete formation, alleles segregate from each other so that each gamete carries only a single copy of each gene

Question 6

allele

Answer 6

contrasting forms of genes/versions

Question 7

punnett square

Answer 7

Used to show the types of gametes (egg and sperm cells) produced by each F1 parent, and shows each possible gene combination for the F2 offspring in the four boxes that make up the square

Question 8

Homologous chromosomes

Answer 8

paired chromosomes, one inherited from each parent, that have the same length, centromere position, and gene order

Question 9

Haploid (what type of cells are haploid)

Answer 9

cells that contain a single set of chromosomes (denoted as n), meaning they have only one copy of each chromosome.

haploid cells are sperm and egg cells

Question 10

Diploid (what type of cells are diploid)

Answer 10

contain two sets of chromosomes—one from each parent. This means they have homologous pairs of chromosomes, where each chromosome has a corresponding partner.
Diploid cells are somatic cells: body cells of most animals and plants

Question 11

Explain five differences between monozygotic and dizygotic twins.

Answer 11

origin
Formed from a single fertilized egg (zygote) that splits into two embryos
Formed from two separate eggs fertilized by two different sperm cells
Genetic similarity
Identical genetic makeup
Genetically similar, like regular siblings
Sex
Always the same sex (unless rare mutations occur)
Can be the same or different sexes
Placenta & Amniotic Sac
May share a placenta but have separate or shared amniotic sacs
Always have separate placentas and amniotic sacs
Appearance
Very similar physical features
Can look different, like any other siblings

Question 12

3 ways triplets form

Answer 12

Three Separate Eggs (Trizygotic Triplets) – Three eggs are fertilized by three different sperm, resulting in three genetically unique siblings.

One Egg Splitting and One Separate Egg (Monozygotic + Dizygotic Triplets) – One fertilized egg splits into identical twins, while another separate egg is fertilized, leading to two identical babies and one fraternal sibling.

One Egg Splitting Twice (Monozygotic Triplets) – A single fertilized egg splits into three embryos, which is extremely rare.

Question 13

examples of dominant traits

Answer 13

Rolling tongue
Curly hair
Short big toe

Question 14

karyotype

Answer 14

the complete set of chromosomes in a cell, arranged in pairs and ordered by size and shape.

Question 15

autosomes vs sex chromosomes

Answer 15

Autosomes are everything but x and y chromosomes, which are the sex chromosomes

Question 16

down syndrome

Answer 16

extra 21 chromosome (3 in total)

Question 17

Klinefelter syndrome

Answer 17

xxy

Question 18

turner syndrome

Answer 18

missing x

Question 19

jacob’s syndrome

Answer 19

xyy

Question 20

edward’s syndrome

Answer 20

3 18 chromosomes

Question 21

superfemale

Answer 21

triple x syndrome

Question 22

patau syndrome

Answer 22

3 13 chromosome

Question 23

cri-du-chat syndrome

Answer 23

one of #5 is partly missing

Question 24

Explain how autosomal recessive disorders work.

Answer 24

An autosomal recessive disorder occurs when an individual inherits two copies of a mutated gene—one from each parent. If a person has only one mutated gene, they are a carrier but do not show symptoms.

Question 25

What is meiosis?

Answer 25

Meiosis is a type of cell division that reduces the chromosome number by half, producing haploid (n) gametes (sperm and egg cells) from a diploid (2n) parent cell. This process ensures genetic diversity and is essential for sexual reproduction.

Question 26

meiosis one steps

Answer 26

Prophase I Chromosomes condense and become visible, and homologous chromosomes pair up (synapsis). Crossing over occurs (exchange of genetic material). Nuclear membrane breaks down, spindle fibers form. Metaphase I Homologous chromosome pairs align at the center (equatorial plate). Independent assortment increases genetic variation. Anaphase I Homologous chromosomes separate and move to opposite poles. Sister chromatids remain together (unlike mitosis). Telophase I & Cytokinesis Two new haploid cells form, each with half the chromosome number. Cells may enter a brief resting phase (interkinesis) before Meiosis II.

Question 27

meiosis two steps

Answer 27

Prophase II Chromosomes condense again. Spindle fibers form, nuclear envelope dissolves. Metaphase II Chromosomes (now consisting of sister chromatids) align at the center. Anaphase II Sister chromatids separate and move to opposite poles. Telophase II & Cytokinesis Four haploid cells are formed

Question 28

meiosis one and two ending

Answer 28

end of Meiosis I: seperation of homologous chromosomes End of Meiosis II: seperation of sister chromatids

Question 29

original parent cell- haploid or diploid

Answer 29

mitosis: diploid meiosis: diploid

Question 30

How many viable sperm cells are created during meiosis? How many viable egg cells are created during meiosis?

Answer 30

4 sperm cells, one egg cell and 3 polar bodies

Question 31

What are polar bodies?

Answer 31

Polar bodies are small, non-functional cells produced during oogenesis (egg cell formation) in female meiosis. They contain excess genetic material but do not develop into eggs. One functional egg and up to 3 polar bodies are produced during female meiosis

Question 32

What is gametogenesis?

Answer 32

the process in which cells undergo meiosis to form gametes.

Question 33

What is oogenesis? Spermatogenesis?

Answer 33

Oogenesis: formation of eggs in females Spermatogenesis: formation of sperm in males

Question 34

Explain how the egg cell in a female and a sperm cell in the male develop prior to the child's birth.

Answer 34

Before birth, sperm cells remain in their undifferentiated form, unlike egg cells, which begin meiosis early but pause until puberty.

Question 35

Explain what happens to the egg and sperm once the child reaches puberty.

Answer 35

Once a child reaches puberty, hormonal changes trigger the maturation of egg and sperm cells, enabling fertility.

Question 36

Who is considered the "Father of Genetics"? What type of plant did he study?

Answer 36

Gregor Mendel, pea plants

Question 37

How did Mendel set up his experiment, starting with the Pt generation to the F2 generation?

Answer 37

Gregor Mendel began his pea plant experiment with the P (parental) generation, crossing true-breeding tall (TT) plants with true-breeding short (tt) plants. The offspring, known as the F1 generation, were all tall (Tt), showing that the tall trait was dominant while the short trait was recessive. Mendel then allowed the F1 plants to self-pollinate, producing the F2 generation. This generation had a 3:1 ratio, tall:short. This proved that the recessive trait had not disappeared but was simply hidden in F1. From this, Mendel developed key principles of inheritance, including the Law of Segregation and the Law of Dominance, forming the foundation of modern genetics.

Question 38

What does "true-breeding" mean?

Answer 38

If self-pollinated, they would only produce offspring that are identical to themselves.

Question 39

Summarize Mendel's principles.

Answer 39

Biological inheritance is determined by genes Each of the traits Mendel studies was controlled by one gene that occurred in two contrasting forms called alleles (versions) Some of these factors are dominant while others are recessive.

Question 40

List the steps to solving dihybrid story problems

Answer 40

-identify traits and alleles -determine parental genotypes -set up a punnett square -determine phenotypic and genotypic ratios -answer questions

Question 41

For each blood type, know: The type of antigen (protein) present

Answer 41

O: none A: a B: b AB: a b

Question 42

Possible genotypes for blood types

Answer 42

O: ii A: I^AI^A, I^Ai B: I^BI^B, I^Bi AB: I^AI^B

Question 43

What type they can donate blood to

Answer 43

O: O, A, B, AB A: A, AB B: B, AB AB: AB, A, B

Question 44

What type they can receive blood from

Answer 44

O: O A: A, O B: B, O AB: A, B, O

Question 45

Antibodies found

Answer 45

O: A, B A: B B: A AB: none

Question 46

What is the rH factor? Why is it important during pregnancy?

Answer 46

If the blood type is positive or negative, it is important during pregnancy because if the fetus is positive and the mother is negative, during the second pregnancy, the mother’s body will begin to attack the fetus due to the antibodies against it.

Question 47

What blood type is the universal donor? Why? What blood type is the universal recipient? Why?

Answer 47

O- because it has no antigens. AB+ is the universal recipient because it produces all of the antibodies.

Question 48

What is the most common blood type? Least common?

Answer 48

Most common: O+ Least common: AB-

Question 49

exception to Incomplete dominance (and give an example)

Answer 49

Incomplete dominance occurs when neither allele in a pair is completely dominant over the other, resulting in an intermediate phenotype in the heterozygous individual. This means that the offspring will show a blending of the two parental traits rather than one being fully expressed. Red flowers (RR) and white flowers (WW) are crossed. The offspring (RW) will have pink flowers, an intermediate color between red and white, because the red allele does not fully dominate the white allele.

Question 50

exception to codominance (give an example)

Answer 50

Codominance occurs when both alleles contribute equally and separately to the phenotype of the organism. In codominance, both traits are fully expressed in the heterozygous individual, without blending. blood types in humans, AB: The A allele and the B allele are both dominant over the O allele. Genotype AA results in blood type A, BB results in blood type B, and AB results in blood type AB, where both A and B alleles are expressed equally in the phenotype.

Question 51

exception to multiple alleles (give an example)

Answer 51

Multiple alleles refer to the presence of more than two alleles for a particular gene, though an individual still only inherits two alleles (one from each parent). These multiple alleles lead to greater genetic diversity and more variations in the traits expressed. Blood types: A, B, O

Question 52

exception to polygenic traits (give an example)

Answer 52

Polygenic traits are traits that are controlled by multiple genes, rather than a single gene. These traits usually show a wide range of phenotypes because the effects of the different genes combine, and the phenotype is influenced by the interaction of all the contributing alleles. Example: skin color (range of skin colors)