AP Bio Unit 5

DNA Polymerase

• requires RNA primers to initate DNA synthesis

• synthesizes new strands of DNA continuously in the leading strand and discontinuously on the lagging strand

Leading Strand

• primase adds a primer across from the 3’ end of the lagging template strand on the outside of the replication fork

• DNA polymerase easily binds and replicates the new strand in one go

• No gaps

Lagging Strand

• primer added across from 3’ end inside of replication fork

• stops working at random intervals and falls off the DNA

• discontinuous replication

Gene

sequence of DNA that codes for a specific protein/trait

Allele

version of a gene

Genotype

• 2 letter combo

• Alleles inherited from parents

Phenotype

• physically seen

• physical traits expressed based on the genotype

Homozygous

• possessing 2 of the same allele

• __ dominant (BB) individuals have 2 dominant alleles

• —- recessive (bb) individuals have two recessive alleles and express the recessive phenotype

Heterozygous

• possessing 2 different alleles

• Bb individuals have a dominant and recessive allele and express the dominant phenotype

Law of Segregation

a parent gives only one allele for a gene to each gamete they produce. random

Law of Independent Assortment

alleles for different genes that are located on different chromosomes segregate independently on each other.

Extranuclear Inheritance

• some traits inherited from DNA found in mitochondria and chloroplasts

• do not follow Mendelian inheritance rules bc they are randomly assorted

Phenotypic Plasticity

• environmental factors can affect which genes are being expressed, when they are being expressed, and how much they are being expressed

• environmental factors DO NOT change the organisms genotype

Penetrance

• likelihood that an organism will actually express its inherited genotype

Expressivity

• the degree to which the phenotype is expressed in an organism

• can be influenced by allele combinations and/or environmental factors that affect gene expression

Autosomal Dominant

• cannot be recessive as 2 affected parents could not have an unaffected offspring

• parents must be heterozygous

Autosomal Recessive

• cannot be dominant as 2 unaffected parents could not have an affected offspring

• parents must be heterozygous

x Linked Dominant

• sex linkage cannot be confirmed

• 100% of affected daughters from affected father suggests X-linked _

X Linked Recessive

• sex linkage cannot be confirmed

• 100% incidence of affected sons from an affected mother suggests x-linked _

Diploid

• 2 full sets/pairs of chromosomes

• chromosome pairs differ in size, shape, genetic info, and centromere location

• one set from each parent

• 2n

Haploid

• cell contains one set of chromosomes

• n

Prophase 1

• nuclear envelope begins to disappear

• fibers begin to form

• DNA coils into visible duplicated chromosomes & made of sister chromatids while paired

• chromatids exchange genetic info w/ chromatids from the other chromosome

• crossing over

• Diploid

Metaphase 1

• double chromosomes remain in pairs, fibers align pairs across the center of the cell

• homologous chromosome pairs

Anaphase 1

• fibers separate chromosome pairs, each double chromosome migrates apart to opposite side

Telophase 1

• nuclear envelope reappears and establishes 2 separate nuclei

• nucleus only contains half of the total info the parent nucleus contained

• chromosomes begin to uncoil

• homologous chromosomes

Prophase 2

• nuclear envelope begins to disappear

• fibers begin to form

• no crossing over

• haploid

Metaphase 2

• fibers align double chromosomes across the center of the cell

• individual, unpaired chromosomes

Anaphase 2

• fibers separate sister chromatids

• single chromosomes migrate to opposite sides of the cell

Telophase 2

• nuclear envelope reappears and establishes separate nuclei

• each nucleus contains single chromosomes

• chromosomes will begin to uncoil

• non-duplicated haploid gametes

Cytokinesis

• separate the 2 cells into 4 daughter cells

• haploid

Random Fertilization

• refers to the concept that any of the genetically unique sperm created by a male can join with any of the genetically unique eggs created by a female

Linked Genes

• typically inherited together

• less likely to be separated during crossing over in meiosis

Sex Linked Traits

• located on sex chromosomes

• determine biological sex in animals

• nonhomologous

• can have different letter designations