Final Flashcards
Asexual reproduction
The creation of genetically identical offspring by a single parent, without the participation of sperm and egg
Chromosomes
The structures that contain most of the organism’s DNA
Sexual reproduction
Each offspring inherits a unique combination of genes from its two parents, making a unique combination of traits
Cell division
The reproduction of cells
Binary fission
Dividing in half
The way the prokaryotes (bacteria and archaea) reproduce
Chromatin
How chromosomes exist most of the time
A diffuse mass of long thin fibers
Combination of DNA and protein molecules
Sister chromatids
Contain identical copies of the DNA molecule on a certain chromosome
After a chromosome duplicates, each chromosome in one is called a sister chromatid
Centromere
Joins the two sister chromatids together
Cell cycle
An ordered sequence of events that extends from the time a cell is first formed from a dividing parent cell until its own division into two cells
Growing stage and actual cell division
Interphase
Most of the cell cycle spent here
Cell’s metabolic activity is high, cell performs functions in organism
Increases supply of proteins, creates more cytoplasmic organelles, and grows in size
Chromosomes duplicate
90% of time
G1 S G2
Grows in G1
Synthesizes DNA and duplicates DNA in S
Prepares for cell division in G2
Mitosis phase (M phase)
The part of the cell cycle when the cell actually divides
10% of time
Mitosis and cytokinesis
Mitosis
The nucleus and its contents, including the duplicated chromosomes, divide and are evenly distributed to form two daughter nuclei
Cytokinesis
The cytoplasm is divided in two
Mitosis spindle
A football-shaped structure of microtubules that guides the separation of the two sets of daughter chromosomes
Centrosomes
Clouds of cytoplasmic material that in animal cells contain centrioles
Spindle microtubules come from here
Prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis
Describe
Cleavage furrow
A shallow groove in the cell surface
Cell plate
In a plant when vesicles containing cell wall material fuse
Growth factor
A protein secreted by certain body cells that stimulates other cells to divide
Density-dependent inhibition
Crowded cells stop dividing
Anchorage dependence
Cells must be in contact with a solid surface to divide
Cell cycle control system
A cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle
Somatic cell
In humans, a typical body cell
A cell that reproduces asexually
Not a sex cell/gamete
Homologous chromosomes
The two chromosomes composing a pair. They both carry genes controlling the same inherited characteristics
Locus
A particular place on a chromosome where a gene is located
Sex chromosomes
X and Y chromosomes
Autosomes
The non-sex chromosomes
Diploid cell
Any cell with two homologous sets of chromosomes
Gametes
The egg and sperm cells
Haploid cell
A cell with a single chromosome set
Fertilization
When a haploid sperm cell and a haploid egg cell fuse
Zygote
A fertilized egg
Diploid
Meiosis
A type of cell division that produces haploid gametes in diploid organisms
Tetrads
Four chromatids
Crossing over
An exchange of corresponding segments between two homologous chromosomes
Begins very early in prophase I of meiosis
Chiasma
A place where two homologous chromatids are attached to each other
Genetic recombination
The production of gene combinations different from those carried by the original chromosomes
Karyotype
An ordered display of magnified images of an individual’s chromosomes arranged in pairs, starting with the longest
Nondisjunction
An occasional mishap when the members of a chromosome pair fail to separate
Could not separate during meiosis I (one side gets three chromosomes the other gets one)
Could not separate during meiosis II (one side gets three chromatids the other gets one)
Deletion
When a fragment of a chromosome is lost
Most harmful
Duplication
When a fragment from one chromosome joins to a sister chromatids or homologous chromosome
Inversion
When a fragment reattaches to the original chromosome but in the reverse direction
Least harmful
Translocation
When a chromosomal fragment attaches to a nonhomologous chromosome
Law of independent assortment
Each pair of alleles segregates independently of other pairs of alleles during gamete formation
