Bio study guide

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asexual reproduction

a mode of reproduction where offspring arise from a single organism, inheriting genes from that parent only

autosomes

chromosomes that are not sex chromosomes, humans have 22 pairs

binary fission

a type of sexual reproduction in prokaryotes where a cell divides into 2 genetically identical cells

cancer

the uncontrolled growth of a cell

centromere

the region of a chromosome where the 2 sister chromatids attach

crossing-over

the exchange of genetic material between homologous chromosomes during meiosis I

cytokinesis

the division of the cytoplasm to form 2 separate daughter cells after mitosis or meiosis

diploid

a cell that contains 2 complete sets of chromosomes (2n), one from each parent

fertilization

the process of a sperm cell joining with an ovum to form a zygote

gametes

sex cells that are haploid

gene

a segment of DNA that codes for a protein or RNA molecule

haploid

a cell that contains only one set of chromosomes

homologous chromosomes

Chromosomes that are similar in size shape and genetic content

independent assortment

the random distribution of homologous chromosomes during meiosis

karyotype

a picture of all the chromosomes in a cell arranged in pairs

meiosis

a type of cell division that reduces the chromosome number by half, creating 4 haploid cells

oogenesis

the process by which ova are produced by the female

ovum

female gamete

sex chromosomes

chromosomes that determine the sex of an individual

sperm

the male gamete

spermatogenesis

the process by which the male produces sperm

spindle

a structure composed of microtubules that segregates chromosomes into the daughter cells during mitosis and meiosis

zygote

a fertilized egg cell formed by the union of a sperm and an ovum

Alleles

different forms of a gene that can live in a different location

co-dominance

a situation in which both animals contribute equally and visibly to the phenotype

complete dominance

a relationship in which one allele is completely dominant over another

dominant allele

an allele that masks the presence of a recessive allele in the phenotype

gregor mendel

father of genetics, known for his work on the pea plants and establishing the principles of genetics

genotype

the genetic makeup of an organism

heredity

the passing of traits from parents to offspring

heterozygous

having 2 different alleles for a particular gene

homozygous

having 2 identical alleles for a particular gene

incomplete dominance

a situation in which the phenotype of the heterozygotes is intermediate between between the phenotypes of individuals homozygous for either allele

multiple alleles

a situation in which a gene has more than 2 alleles

phenotype

the physical expression of a genotype

polygenic inheritance

an additive effect of 2 or more genes on a single phenotypic character

punnet square

a diagram used to predict the genotype and phenotype combinations of a genetic cross

recessive allele

an allele that is masked by the presence of a dominant allele

sex-linked traits

traits that are determined by genes located on the sex chromosomes

anti-codon

a 3 nucleotide sequence on the tRNA that pairs with the complementary codon on mRNA during translation

codon

a 3 nucleotide sequence on tRNA that specifies a particular amino acid

DNA helicase

an enzyme that unwinds the DNA double helix during DNA replication

DNA polymerase

an enzyme that synthesizes new DNA strands using a template strand

Hydrogen bonds

weak bonds that hold the 2 strands of DNA together between complementary bases

nucleotide

the building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenius base

replication fork

the Y-shaped region where the DNA is split into 2 strands and being replicated

RNA polymerase

An enzyme that synthesizes RNA from a DNA template during transcription

transcription

The process of copying a segment of DNA into RNA

translation

The process by which mRNA is decoded and a protein is produced

Adaptation

A trait that increases an organisms fitness in its environment

Darwin

created the theory of natural selection

Divergence

The accumulation of differences between groups which can lead to the formation of new species

gradualism

the theory that evolution occurs slowly but steadily

homologous structures

features that share common ancestry

Lamarck

use/disuse

Lyell

geologist

natural selection

survival of the fittest

paleontologist

scientist who studies fossils

punctuated equilibrium

the theory that species evolve through short periods of rapid change

reproductive isolation

when species cant interbreed

speciation

formation of a new species

vestigial structures

structures of little use

wallace

evolution by natural selection

population

a group of the same species living in the same area

exponential growth

a growth pattern that proceeds rapidly

logisical growth

a slow but long period of growth

carrying capacity

the maximum population size that a environment can sustain

directional selection

a type of natural selection that favors individuals with extreme variation of a trait

stabilizing selection

a type of natural selection that favors average individuals

non-random mating

species choosing who they mate with

genetic drift

random changes in allele frequencies

gene flow

alleles flowing in and out of a population