Shared Flashcard Set

Details

Bio Ch. 13
Biology Eighth Edition Vocab
57
Biology
Undergraduate 1
11/14/2010

Additional Biology Flashcards

 


 

Cards

Term
Genetics
Definition

The scientific study of heredity and variation

 

Term

Heredity


Definition
the transmission of traits from one generation to the next
Term
Variation
Definition
is demonstrated by the differences in appearance that offspring show from parents and siblings
Term
Genes
Definition
the units of heredity, and are made up of segments of DNA
Term
Gametes
Definition
Genes are passed to teh next generation through these reproductive cells (sperm and eggs)
Term
Locus
Definition
The certain chromosomal location for each gene
Term
DNA
Definition

It is packaged into chromosomes annd one set of chromosomes is inherited form each parent

 

Term
Asexual reproduction
Definition
One parent produces genetically identical offspring by mitosis
Term
Clone
Definition

a group of genetically identical individuals from the same parent

 

Term
Sexual Reproduction
Definition
Two parents give rise to offspring that have unique combinations of genes inherited from the two parents
Term
Life Cycle
Definition

the generation-to-generation sequence of stages in teh reproductive hsitory of an organism

 

Term
Somatic Cells
Definition
(Any other cell than a gamete) have 23 pairs of chromosomes
Term
Karyotype
Definition
an ordered display of the pairs of chromosomes from a cell
Term
Homologous chromosomes
Definition
two chromosomes in each pair, or homologs
Term
Sex Chromosomes
Definition
The X and Y chromosomes
Term
Autosomes
Definition
The 22 pairs of chromosomes that do not determine sex
Term
Diploid Cell
Definition
(2n) Has two sets of chromosomes. For humans Diploid number is 46 (2n=46)
Term
Haploid
Definition
A gamete (sperm or egg) contain a single set of chromosomes which is called a haploid
Term
Fertilization
Definition
The union of gametes (the sperm and the egg)
Term
Zygote
Definition
The fertilized egg is called a zygote an dhas one set of chromosomes from each parent. Zygote produces somatic cells by mitosis and develops into an adult
Term
Meiosis
Definition
Gametes are the only types of human cells produced by meiosis, rather than mitosis. Meiosis results in one set of chromosomes in each gamete (4 haploids)
Term
The Human Life Cycle
Definition
[image]
Term
The Animal life cycle
Definition
Meiosis produces gametes, which undergo no further cell division before fertilization. Gametes are the only haploid cells in animals. Gametes fuse to form a diploid zygote that divides by mitosis to develop into a multicelullar organism
Term
The Plants and some Algae Life Cycle
Definition
[image]
Term
Most fungi and some protists Life Cycle
Definition
Only diploid stage is the single-celled zygote; there is no multicellular diploid stage. Zygote produces haploid cells by meiosis. Each haploid cell grows by mitosis into a haploid multicellular organism. Haploid adult produces gametes by mitosis
Term
Sporophyte
Definition
The diploid organism which makes haploid spores by meiosis
Term
Spores
Definition
Haploids made by sporophytes by meiosis
Term
Gametophyte
Definition
Each spore grows by mitosis into a haploid multicellular organism called a gametophyte
Term
Meiosis I and Meiosis II
Definition
The two cell divisions result in four daughter cells, rather than the two daughter cells in mitosis, each with only half as many chromosomes as the parent cell
Term
Meiosis I
Definition
Homologues chromosomes separate and results in two haploid daughter cells with replicated chromosomes; It is called teh reductional division
Term
Meiosis II
Definition
Sister chromatids separate and results in four haploid daughter cells with unreplicated chromosomes; it is called the equational division
Term
Interphase
Definition
Chromosomes are replicated to form sister chromatids; Sister chromatids are genetically identical and joined at the centromere. The signle centrosome replicates, forming two chromosomes
Term
Prophase I
Definition

Occupies more than 90% of the time required for meiosis.

Chromosomes begin to condense

Synapsis Occurs

Crossing over occurs

Each pair of chromosomes forms a tetrad

 

Term
Synapsis
Definition
Homologous chromosomes loosely pair up, aligned gene by gene (only occurs in Prophase I)
Term
Chiasmata
Definition
X-shaped regions where crossing over occured
Term
Tetrad
Definition
When each pair of chromosomes forms a group it is a group of four chromatids
Term
Metaphse I
Definition

Tetrads line up at the metaphase plate.

Microtubules from each poles are attached to teh kinetochore

Term
Anaphse I
Definition

Pairs of homologous chromosomes separate.

One chromosome moves toward each pole, guided by teh spindle apparatus. (sister chromatids remain attached at the centromere and move as one unit toward the pole)

Term
Telephase I
Definition
Each half of the cell has a haploid set of chromosomes; Each chromosome still consists of two sister chromatids.
Term
Cytokinesis
Definition

Occurs simultaneously, forming two haploid daughter cells.

In animal cells, a cleavage furrow forms; in plant cells, a cell plate forms

 

Term
Prophase II
Definition
Spindle apparatus forms. Chromosomes (each still composed of two chromatids) move toward teh metaphase plate
Term
Metaphase II
Definition
Sister chromatids are arranged at the metaphase plate. (no longer genetically identical because of crossing-over)
Term
Anaphase II
Definition
Sister chromatids separate toward opposite poles
Term
Telophase II
Definition

Chromosomes arrive at opposite poles.

Nuclei form, and the chromosomes begin decondensing

Term
Cytokinesis
Definition
Separates teh cytoplasm. End of meiosis, there are four daughter cells, each with a haploidset of unreplicated chromosomes
Term

Mitosis vs Meiosis

Definition
Mitosis conserves the number of chromosome
sets, producing cells that are genetically identical
to the parent cell Meiosis reduces the number of chromosomes sets
from two (diploid) to one (haploid), producing cells that differ genetically from each other and from the parent cell
Term
Three events unique to Meiosis
Definition
- Synapsis and crossing over in prophase I:
Homologous chromosomes physically connect
and exchange genetic information
– At the metaphase plate, there are paired
homologous chromosomes (tetrads), instead of
individual replicated chromosomes
– At anaphase I, it is homologous chromosomes,
instead of sister chromatids, that separate
Term
Cohesins
Definition
Protein complexes that keep sister chromatids of a single chromosome to stay together through meiosis I. Broken up in Anaphase I and II
Term
Shugoshin
Definition
Protects cohesins at the centromere at anaphase I, thus maintainig the attachment between sister chromatids and ensuring that they separate properly during meiosis II
Term
Mutations
Definition
(chanes  in an organism's DNA) are the original source of genetic diversity. Creates different versions of genes called alleles. Reshuffling of alleles during sexual reproduction produces genetic variation
Term
Three mechanisms contribute to genetic variation:
Definition

- Independent assortment of chromosomes

- Corssing Over

- Random fertilization

Term
Independent assortment
Definition
Each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of the otehr pairs
Term
Possible cominations of chromosomes
Definition

Formula: 2^n

 

For humans (n=23), there are more than 8 million (2^23) possible combinations of chromosomes

Term
Recombinant chromosomes
Definition
Produced by crossing over and they are combined genes inherited from each parent
Term
Crossing Over
Definition

Homologous portions of two nonsister chromatids trade places.

Combines DNA from two parents into a single chromosome

(only occurs in Prophase I)

Term
Random fertilization
Definition

Adds to genetic variationb ecause any sperm can fuse with any ovum (unfertilized egg).

 

The fusion of two gametes (each with 8.4 million possible chromosome combinations) produces a zygote with any of about 70 trillion diploid combinations

Term
Natural selection results in...
Definition
the accumulation of genetic variations favored by the environment. Sexual reproduction contributes to this genetic variation in a population.
Supporting users have an ad free experience!