Introduction to Biology - Chapter 9 (Sexual Reproduction & Meiosis)

Reproduction (characteristic of life)

transmit of DNA to next generation

Reproduction Types

sexual and asexual

Sexual Reproduction

fertilization of female gamete (egg) by male gamete (sperm)

Zygote

fertilized egg (gamete)

Somatic cells

all cells in our body EXCEPT sex cells

Mitosis

division of SOMATIC cells

Mitosis produces

diploid cells

Meiosis

division of SEX cells

Meiosis produces

haploid cells

Meiosis purpose

production of gametes/sex cells

The Cell Cycle

interphase and mitosis

Interphase stages

G1, S, G2

G1 phase

Cell growth

S phase

DNA synthesis

G2 phase

more growth, prep for mitosis

Go phase

resting phase

Differentiation (Exit from Cell Cycle)

- cells become specialized in structure and function

- irreversible

Quiescence (Exit from Cell Cycle)

- inactivity, resting

- reversible

Mitosis stages

prophase, metaphase, anaphase, telophase

Malignant Neoplasms

- cancer

- spread to other areas of the body

Metastasis

spread of malignant cells

Cytokinesis

division of the cytoplasm

Pollination

sexual reproduction in plants

Mitosis and Meiosis similarities

dna replicates once, produce offspring, cell division

Mitosis and Meiosis Differences - Mitosis

- 4 stages in total (plus interphase

- happens in somatic cells

Mitosis and Meiosis Differences - Meiosis

- 8 stages in total (plus interphase)

- happens in germ cells

Chromosome

- threadlike structure

- made of protein & DNA

Histone

- structural protein

- provides structural support for chromosome

Centromere

- middle region that holds chromosome together

- Has DNA

Short arm (chromosome)

- top half

- p arm

Long arm (chromosome)

- bottom half

- q arm

Telomere (chromosome)

- end of a shoelace

- ends of chromosomes

- role in cell aging & protection

Genes

DNA sections that code for specific proteins

Alleles

different version of a gene

Loci (locus)

tells where on a chromosome a specific gene is located

Karyotype

arrangement of chromosomes pairs by size

23 pairs

How many pairs of chromosomes do humans have?

23 pairs equals

46 chromosomes

Female sex chromosome

X chromosome

Female sex chromosome pair

XX

Male sex chromosome

Y chromosome

Male sex chromosome pair

XY

Homologous chromosomes

Chromosomes that have the same genes in the same order

Non-homologous chromosomes

different chromosomes that do not pair up during meiosis/different gene sets

Male homologous pairs

22

Female homologous pairs

23

Haploid

one set of chromosomes

Diploid

2 full sets of chromosomes

(mother & father)

Heterozygous

having two different versions for a gene

Homozygous

having two identical versions for a gene

Dominant genes

genes that are seen/expressed

Recessive genes

genes that are present but may NOT be seen/expressed

Errors in Meiosis can cause

chromosomal abnormalities & genetic disorders (mutations)

Nondisjunction

chromosomes fail to separate

Extra autosomes (somatic cells)

Down Syndrome

1. What is meiosis?

division of sex cells

2. During which stage does DNA synthesis (replication) occur?

S (synthesis) phase

3. Explain the process of sexual reproduction in plants

Pollination:

Pollen (male gametophyte) is transferred to the stigma (female part).

4. (a). Draw the structure of a chromosome and label each part

Chromatids: Two identical arms (sister chromatids) held together by a centromere.

4. (b). Draw the structure of a chromosome and label each part

Centromere: Constricted middle region where spindle fibers attach.

4. (c). Draw the structure of a chromosome and label each part

Telomeres: Protective caps at chromosome ends.

4. (d). Draw the structure of a chromosome and label each part

P & Q Arms: Short/top half (p) and long/bottom half (q) arms extending from the centromere.

5. What is the function of the centromere in chromosomes?

Holds sister chromatids together before separation.

6. Name one type of chromosomal abnormality from errors in meiosis

Nondisjunction

7. Mutations are most likely to occur during which stage of the cell cycle?

Anaphase or S phase

8. What is a FALSE statement regarding telomeres?

They are located at the center of the chromosome

9. Each of the following statements is true regarding cytokinesis, Except

None of the above

10. What is a FALSE statement regarding the G0 phase,

Cells synthesize DNA during this phase