Meiosis and Heredity

Question 1

Spermatogenesis

Answer 1

Sperm production

Question 2

Mitosis and cell division

Answer 2

Somatic cells produce two daughter cells containing 23 identical chromosome pairs (diploid); in seminiferous tubules, stem cells undergo mitosis

Question 3

Meiosis

Answer 3

Two cycles of cell division (meiosis I and II); produces four haploid cells each with 23 individual chromosomes; during fertilization, 23 paired chromosomes regained with 23 paternal and 23 maternal associated (synapsis)

Question 4

Spermiogenesis

Answer 4

Differentiation of immature male gametes into physically mature spermatozoa

Question 5

Oogenesis

Answer 5

Begins before birth, accelerates at puberty, ends at menopause; produces: one functional ovum (with most of original cytoplasm): one primary oocyte created during meiosis I, one secondary oocyte created in meiosis II and released (does not complete meiosis II until fertilization); two or three polar bodies (nonfunctional; disintegrate)

Question 6

Inheritance

Answer 6

Transfer of genetically determined characteristics from generation to generation

Question 7

Genetics

Answer 7

Study of mechanisms responsible for inheritance

Question 8

Genotype

Answer 8

Genes on chromosomes within cells

Question 9

Phenotype

Answer 9

Anatomical and physiological expressions of genotype

Question 10

Karyotype

Answer 10

Entire set of chromosomes

Question 11

Chromosome structure

Answer 11

Homologous chromosomes have same structure: carry genes (each located at equivalent position (locus) on chromosome, form (allele) of two genes may be same or different, each human chromosome has ~1000 pairs)

Question 12

Homozygous

Answer 12

Same alleles

Question 13

Heterozygous

Answer 13

Different alleles

Question 14

Strict dominance

Answer 14

Any dominant allele will be expressed in phenotype; recessive alleles phenotypically expressed if same allele is present on both homologous chromosomes

Question 15

Punnett squares

Answer 15

Grid showing possible offspring genotypes

Question 16

Polygenic inheritance

Answer 16

Interactions among several genes determine phenotypic characteristics; cannot use simple punnett square to predict phenotype

Question 17

Codominance

Answer 17

Heterozygous individuals (for given trait) exhibit both phenotypes for trait

Question 18

X-linked inheritance

Answer 18

X chromosome much larger that Y and carries more genes; characteristics are X-linked (or sex linked) because no corresponding allele on Y chromosome

Question 19

Abnormal genes

Answer 19

1.4 million single-base differences (single nucleotide polymorphisms); some are inconsequential but others relate to specific diseases

Question 20

Abnormal chromosomes

Answer 20

involve thousands of genes and are usually lethal; some autosomal chromosome abnormalities do not result in prenatal morality

Question 21

Trisomy 21 (down syndrome)

Answer 21

Three copies of chromosome 21; individuals have limited brain function and life span

Question 22

Klinefelter syndrome (sex chromosome pattern XXY)

Answer 22

Phenotype is male but has reduced androgen production; testes fail to mature (sterile) and breasts slightly enlarged

Question 23

Turner syndrome (sex chromosome pattern XO)

Answer 23

Single sex chromosome (monosomy); no maturational changes at puberty and nonfunctional ovaries

Question 24

Human genome

Answer 24

full set of genetic material (DNA) in our chromosomes; estimated 20,000-25,000 genes; ~10,000 gene disorders described; collectively affect 1 in 200 births