Honors Bio Quarterly #3

(this set doesn't have the 'molecular bio + biotech' part of the study guide)

Chromosome

Chromosome

condensed chromatin

Chromatid

one side of the duplicated chromosome (sister chromatids)

Chromatin

DNA tightly coiled around histones

Centromere

location where the sister chromatids attach to each other

Spindle Fibers

protein structures that move chromosomes

Cell Cycle

cycle in which a cell grows and replicates

Apoptosis

programmed cell death

Histones

proteins the DNA/chromatin is wrapped around

Centrioles

cell organelles near the nucleus that aid in the development of spindle fibers in cell division

Homologous Chromosomes

pair of chromosomes that are the same size, appearance, and genes

Karyotypes

photograph of all chromosomes of an organism

How can you determine if the karyotype represents a male or female?

chromosome pair 23 tells you ⟹ XY is male while XX is female

What would a normal karyotype look like?

46 chromosomes and 23 pairs (in humans)

Trisomy

an organism has an extra chromosome

Monosomy

an organism has a (1) missing chromosome

Nondisjunction

the process in which the chromatids/chromosomes don't separate correctly

Crossing Over

the exchange of DNA between homologous chromosomes during Prophase I of meiosis

Recombinant

mixed DNA

Tetrad

structure containing 4 chromatids that form during meiosis

Gametes

reproductive cells; sperm/egg cells

Fertilization

the fusion of an egg and sperm cell

Zygote

a diploid cell that results from fertilization; fertilized egg

Interphase

phase where the cell grows, performs normal functions, and prepares for division; can be broken down phases

G1 Phase

phase right after mitosis, the cell grows and functions normally

G0 Phase

nondividing state occupied by cells that don't divide (S phase and G2 phase don't occur in organisms that go through G0 phase)

S Phase

phase after G1, when the DNA is replicated (DNA polymerase does this)

G2 Phase

phase before mitosis/cytokinesis, cell grows even more and prepares for division

Mitosis/Meiosis

division of the nucleus

Prophase

chromosomes condense and become visible; centrioles go to opposite sides; spindle fibers form; nuclear envelope dissolves

Metaphase

chromosomes line up in the middle (or equator) of the cell

Anaphase

sister chromatids are pulled to opposite ends

Telophase

chromosomes decondense; new nuclear membrane forms; spindle fibers are broken down

Cytokinesis

division of cytoplasm

Cleavage Furrow

forms when animal cells go through cytokinesis; area where plasma membrane pinches in and separates the cell

Cell Plate

forms when plant cells go through cytokinesis; midline of dividing cell; becomes the cell wall

End products of Mitosis and Cytokinesis

2 daughter cells; diploid; body cells

Meiosis

cell division that produce gametes

Prophase I

homologous chromosomes pair up; tetrads form; crossing over occurs; spindle fibers form

Metaphase I

homologous chromosomes line up in the middle of the cell (by centromere)

Anaphase I

homologous chromosomes separate (haploid cells are made)

Telophase I

2 nuclei form; cytokinesis occurs; results in 2 haploid cells

Prophase II

nuclear membrane disappears; chromosomes condense; centrioles move to opposite poles; spindle fibers form

Metaphase II

chromosomes line up at the equator

Anaphase II

sister chromatids are broken apart into opposite poles

Telophase II

chromatin forms; nuclear membrane reappears; cytokinesis occurs; results in 4 haploid cells

End products of Meiosis and Cytokinesis

4 daughter cells; haploid; egg or sperm cells

Asexual Reproduction

reproduction with 1 parent cell; parent's clone

Sexual Reproduction

reproduction with 2 parents; unique offspring

Diploid

a cell having 2 sets of chromosomes

Haploid

a cell having only 1 set of chromosomes (no homologous pairs in a cell)

Genes

parts of DNA + have the ability to code for a trait

Alleles

variation of a gene

Autosomes

chromosome pairs 1-22; every chromosome that isn't a gamete

Mutations

changes in the DNA sequence (not necessarily bad)

Sex Chromosomes

23rd pair of chromosomes; XX or XY

True Breed

homozygous

P Generation

parents (usually true breeds)

F1 Generation

children of the P generation

F2 Generation

children of the F1 generation

Punnett Squares

the probability of passing traits to offspring

Law of Dominance

the dominant trait is expressed

Law of Segregation

1 allele comes from each parent

Law of Independent Assortment

(in a dihybrid cross) the 2 genes aren't related

Complete Dominance

the heterozygote expresses the dominant gene

Incomplete Dominance

the heterozygote expresses a mix of the dominant and recessive gene

Codominance

when the heterozygote expresses both phenotypes

Genotype

combination of alleles

Phenotype

physical expression of a trait

Homozygous

same allele (RR or rr)

Heterozygous

different alleles (Rr)

Pedigree Chart inheritance patterns

• Dominant ⟹ when a generation isn't skipped

• Recessive ⟹ when a generation is skipped

• Mostly males have the X-linked gene

Blood Types

• AO/BO ⟹ heterozygous

• AA/BB ⟹ homozygous dominant

• OO ⟹ homozygous recessive

Product Rule

when 2 events occur together (AND), multiply the probabilities together

P(A and B) = P(B) * P(A)

Sum Rule

when two events occur independently (OR), add the probabilities together

P(A or B) = P(A) + P(B)

Natural Selection

individuals with higher fitness survive and reproduce

Natural Selection is identified by

• Genetic variation in populations

• Competition for resources

• Differential reproductive success

• Individuals with higher fitness will pass on their traits to the next generation

• Results in changes in the population over time

Types of Natural Selection

directional, disruptive, stabilizing

Directional Selection

occurs when natural selection favors one of the extreme variations of a trait

Disruptive Selection

favors individuals at both extremes of the phenotypic range

Stabilizing Selection

natural selection that favors intermediate variants

Gene Flow

change in allele frequency by migration into and out of populations (type of evolution)

Genetic Drift

change in the allele frequency by chance alone (type of evolution)

Bottleneck Effect

change in allele frequency after a catastrophe that wipes most of the population (type of genetic drift)

Founder Effect

change in allele frequency as a result of a small subset of the population starting a new colony (type of genetic drift)

Morphology

body characteristics

Ecomorphs

groups referred to as ecological morphotypes

Adaptive Radiation

the evolution of several divergent forms from a primitive and unspecialized ancestor

Gene Pool

all of the allele for the genes of the traits in a population

Alleles _____ have to have the same frequency.

DON'T