Chapters 8-10 Flashcards
Cell division
Reproduction. Produces two “daughter” cells that are genetically identical to each other and to the original “parent” cell.
Chromosomes
Structures that contain most of the cell’s genetic information in the form of DNA.
Asexual reporduction
Creation of genetically identical offspring by a single parent. Gives rise to a clone.
Clone
A group of genetically identical individuals.
Sexual reporduction
Requires the fusion of gametes.
Zygote
Fertilized egg.
Binary fission
“Dividing in half.”
Stages of a binary fission in a prokaryote
- As chromosome is duplicating, one copy moves toward the opposite end of the cell.
- Cell elongates
- Duplication is complete; plasma membrane pinches inward, which forms a cell wall, which divides parent cell into two daughter cells.
Cell cycle
Ordered sequence of events that run from the instant a cell is first formed from a dividing parent cell until its own division into two cells.
2 main stages of cell cycle
- interphase: growing phase. Cell doubles in its cytoplasm and replicates its DNA
- mitotic phase: actual cell division
interphase
Period of cell growth when cell synthesizes new molecules and organelles.
- G(1) phase: “first gap”
- S phase: “synthesis” of DNA - aka DNA replication
- G(2) phase: “second gap”
Mitosis phases
Prophase, prometaphase, metaphase, anaphase, and telophase
Prophase
Chromatin fibers in nucleus become more tightly coiled and folded, forming discrete chromosomes.
Metaphase
Mitotic spindle is fully formed. Chromosomes line up on metaphase plate.
Anaphase
Chromosomes separate and move towards the poles
Telophase
Cell elongation continues. Forms a cleavage furrow, then splits.
Cytokinesis
Division of cytoplasm and usually occurs simultaneously with telophase.
Anchorage
When cells must be in contact with a solid surface to divide.
Cell cycle control system
Set of molecules that both triggers and coordinates key events in the cell cycle.
Tumor
A mass of abnormally growing cells within otherwise normal tissue.
Benign tumor
Tumor where abnormal cells remain at their original site.
Malignant tumor
Mass of abnormally reproducing cells that can spread into neighboring tissues and invade other parts of the body. A individual with this type of tumor is said to have cancer.
Metastasis
The spread of cancer cells beyond their original site.
Somatic cell
A typical body cell in humans. Usually has 46 chromosomes. Changes in these cells do not influence gametes.
Homologous chromosomes
The two chromosomes that are twins of each other. Every diploid cell has pairs of these.
Autosomes
Chromosomes other than sex hormones.
Life cycle
Sequence of generation-to-generation stages in the history of an organism.
Gametes
Egg and sperm cells. Only cells of the human body that are not produced by mitosis.
Haploid cell
Cell with a single chromosome set.
Meiosis
Type of cell division that produces haploid gametes in diploid organisms. Has to consecutive cell divisions: mieosis I and meiosis II
meiosis phase
Meiosis I separates the members of each homologous pair and produces two daughter cells, each with one set of chromosomes.
Meiosis II is essentially the same as mitosis:
-In each of the cells, the sister chromatids of each chromosome separate.
The result is a total of four haploid cells.
Crossing over
Exchange of corresponding segments between nonsister chromatids of homologous chromosomes.
Recombinant chromosomes
Result of crossing over. Chromosomes that carry DNA from two different parents.
Nondisjunction
In which members of a chromosome pair fail to separate.
Karyotype
Ordered display of magnified images of an individual’s chromosomes arranged in pairs.
Trisomy 21
when there are three number 21 chromosomes, which results in 47 chromosomes in total.
Deletion
Occurs when a chromosomal fragment (with its genes) becomes detached.
In typical prokaryotes, most genes are carried on…
one circular DNA molecule that, with associated proteins, constitutes the organism’s chromosome.
Heredity
Transmission of traits from one generation to the next.
Genetics
Scientific study of heredity.
Character
A heritable feature that varies among individuals
Trait
Each variant for a character
True-breeding
Where self-fertilization produces offspring all identical to the parent.
Hybrds
Offspring of two different varieties
Cross
Hybridization. Cross-fertilization itself
P generation
True-breeding parents
F(1) generation
Hybrid offspring of P generation
F(2) generation
When F(1) plants self-fertilize or fertilize each other
Alleles
Alternative versions of a gene
Homozygous
When an organism that has two identical alleles for a gene
Heterozygous
When an organism that has two different alleles for a gene.
Dominant allele
When two alleles of an inherited pair differ, the dominant allele determines the organism’s appearance