Chapter 5   GENETICS AND REPRODUCTION

 

I. Objective 36

B.16 The student will employ appropriate terminology when describing sexual reproduction.

B.17 The student will relate methods of sexual reproduction in plants.

B.18 The student will relate methods of sexual reproduction in animals.

 

A.     Reproduction- the process of passing on genetic information

B.     Methods of reproduction

  1. Sexual- requires the union of two cells
  2. Asexual- does not require information from two cells

C.     The process

Animals

  1. sex cells- gamates

a.       ovum female gamates called egg

b.      Spermatozoan male gametes

  1. Fertilization- the combination of the two gamates
  2. Now called a Zygote
  3. As it develops it becomes a EMBRYO
  4. After eight weeks it becomes a FETUS.

Plants

  1. Fertilization occurs when

a.       Pollen from the Stamen (male)

b.      Combines with Pistil (Female)

c.       The developing embryo is called a SEED

d.      The ovary of the plant develops into fruit.

e.       Germination- when the seed splits and begins to grow

 

II. Objective 37 GENETICS

B.20 The student will explain the chemical basis of genetic expression.

 

A.     DNA- Deoxyribonucleic acid- the blue print for the organism

  1. nitrogen bases- adenine, quanine, cytosine, and thymine
  2. shape- double helix
  3. is duplicated through the process replication – where the double strands uncoil

B.     RNA- ribonucleic acid- used to transfer the information or blue print

1. nitrogen base-uracil

C.     Process of producing a new cell (PMAT)

  1. Mitosis- splitting of a cell’s nucleus

a.       Interpahse- a time of cell growth between mitosis cycles

b.      Prophase- chromosomes thicken and become visible

c.       Metaphase- chromosomes pair and line up (meta- middle)

d.      Anaphase-chromosomes separate and produce chromatids

e.       Telophase-a nuclear membrane forms around each set of chromosomes

  1. Cytokinesis- splitting of a cells cytoplasm

 

III. Objective 38

B.23 The student will apply genetic concepts

 

A.     Heredity- the passing of traits from parent to offspring

  1. discovered by Gregor Mendel
  2. Can be predicted using punnett square
  3. Gene- is a DNA segment that controls a singe trait

a.       dominate- will hide other traits- indicated by Capital letters

b.      Recessive- will be hidden by the dominate – indicated by lower case letters

c.       Codominance- when two traits can be seen

  1. Genotype- is the type of genetic makeup  (What letters does it have?)
  2. Phenotype- the expression of the trait ( actual physical characteristics)
  3. Homozygous- if both alleles are the same

a.       Homozygous dominant (TT)

b.      Homozygous recessive (tt)

  1. Heterozygous- when the alleles are mixed

a.       the dominant trait will be expressed (Tt)

8. Examples

 

T

T

 

 

T

T

 

 

T

t

t

Tt

Tt

 

T

TT

TT

 

T

TT

Tt

t

Tt

Tt

 

t

Tt

Tt

 

t

Tt

tt

 

 

IV. Objective 39  GENETIC DISEASES

B.21  The student will relate chemical mutations to genetic diseases.

 

 

A.     Genes consist of  nucleotides

B.     Mutation- a change in one of the base pairs of the DNA

  1. Point mutation- a specific base may be substituted for another
  2. Frame-shift mutation- involves a base that may be lost resulting in a different code.
  3. Mutagens

a.       are factors that cause changes in DNA

b.      common mutagens

source

Example

Radiation

x-rays, ultraviolet light from the sun, nuclear reactors, weapons

Drugs

Thalidominde, LSD, aspestos, saccharine, formaldehyde, mustard gas

Viruses

Rous sarcoma

 

C.     Types of disorders.

  1. Down Syndrome- occurs in 21 chromosome
  2. Turner syndrome- only an X chromosome received.
  3. Klinefelter Syndrome- results from XXY combination
  4. Phenylektonuria (PKU)- lacks an enzyme can cause brain damage
  5. Cystic fibrosis (CF)- pairing of two recessive genes
  6. Dyslexia- reads backward and confuses letters
  7. Huntington’s Disease-loss of muscle control and mental ability
  8. Hemophilia- results from a single gene- persons can’t clot blood.
  9. Color blindness- sex linked trait
  10. Sicklecell anemia- occurred by nitrogen base substitution

D.     Mutations are usually bad- however some are good like plant mutation in order to make it better in a given environment

 

V. Objective 40  Asexual Reproduction

B.13  The student will identify asexual reproduction, its method, and its application to society.

 

 

A.     Asexual reproduction- involves only a single parent organism. it products an exact replica

  1. Budding-occurs when part of the cytoplasm breaks off
  2. Vegetative propagation- when part of the plant is broken off
  3. Spore formation- when fungi or mosses reproduce
  4. Binary fission- involves the direct division of a parent cell into two separate organisms

 

VI. Objective 41  MEIOSIS

B.15 The student will explain sexual reproduction at the cellular level.

 

  1. Sexual Reproduction- involves the combination of genetic material from two parents

1.      Gametes are produced through the process of Meiosis

2.      are fused into one in the fertilization

3.      In MEIOSIS- A diploid parent produces a haploid. The number of chromosomes is decreased by half

4.      In MITOSIS- a diploid parent produces a diploid parent

 

 

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