inheritance

haploid

• 1 single set of chromosomes

• n number of chromsomes

• chromsomes nto in a homologous pair

• each chromsome is different in size shape and genes n loci

diploid

• 2 sets of chromsomes

• homoglous pair

homologous pair

• pair of chromsomes in diploid cells

• one inhertited from father

• one inheritied from mother

• same size n length

• same position of centromere

reduction divison

• maintains chromsome number from parents to offspring from gen to gen

• gives genetic variation in gametes

• fertlisation - gametes fuse tgt to make zygoat

• meisis produces halpoid gametes during sex repl

importance of meisosi

• reduction division

• pproduces gametes that are haploid

• maintains a diploid number of chromosomes in each generation

• produces genetic varation in offspring

crossing over

• exchange of genetic material

• neew combinastions of alleles within each chromosome

• gentic variation occurs

sex linked gene

alleles / gene carried on sex chromosomes

usually x chromosome

phenotype

• observable characteristic

• inlfucned by geneotype n enviroment

genotype

ales posssesed in an organism

locus

position of a gene on a chromosome

codominance

boht allels r fully expressed in phenotype

mroe than 2 phenotypes r possible

allele

• alternate form of a gene

gene

• segment of dna that codes for a polypeptide

homozygous

• both alleles of a gene are the same

reccessive

• only expressed f there r two copies of it and dominant is absent

test cross

dominant phenotype is crossed with a homozygous reccessive

f1

• homozygous dom crossed with homozygous reccessive

• all of this gen is heterozygous

f2

two f1 gen crossed

how does meiosis casue genetic variaiton

1. crossing over at prophase 1 between non siter chromatids at chiasmata

2. independent assortment of hom chromo at metaphase 1

   • results in gamtes that r gentically unique

prophase 1

• condensation of chromatin, centrosomes move to oppsoite poles, nucelar envelope breaks down, nucelolus dissaperas, spindle fibers form,

• attach to centromere and pulls

• synapsis occurs, homologous chromo pair up and coil around, forming bivalent

• crossing over of non sister chroatids occur at chiasmata

• exchange of genes

metaphase 1

• centrosomes reach opposite poles

• spindle fibers fully form and attach to chromsomes at centroeres

• bivalents line up at the equator

• chromsomes line up in hairs

• independent assortment of homologous chromsoome pairs occur

anaphase 1

spindle fiebrs shroten

homologius chrormorme seperate

ech chromo pulled to opp poles centromere leading

telophase 1

• reach poles

• chromosomes partially decondense

• nucleolus reforms

• nucelar envelope reassembles

• spindle fibers break down

• cytokinese occur

• 2 haploid cells formed

cytokinesis animals

divison of cytoplasm

• cell membrane drawn tgt

• contractile rings of microfilaments

• forms a cleveage furrow

• continues contracting

• drawstrong effect

cytokineses plant cells

• vesicles transport to equator

• form the cell plate at equator

• cell wall is laid dwn

• cytoplasm is divided into teo

• organelles are shared out

prophase 2

• condesnation of chromatin

• nuclear envelope breaks down, nucelolus dis, spindle fibers form

• attach to centromere n pull

metaphase 2

centrosomes reach oppsotie poles

spindle fibers fully form

chromo line up at equator, right angles to equator

attach to spindle fibers

independent assortment of sis chromatids occur

anaphase 2

• spindle microtubles shorten

• chromatids pulled to opp poles

• centromeres do not divide

telophase 2

• chromo reach poles

• Chromosomes decondense

• Nucleolus reforms 

• Nuclear envelope reassembly 

• Spindle fibers breaks down 

• Cytokinesis occurs 

• Number of chromosomes in each daughter cell are now halved

• 4 haploid cells formed

albinism

Albinism TYR gene Tyrosinase Lack the pigment with melanin  Amino acid tyrosine is converted to DOPA by enzyme tyrosinase DOPA is converted to dopaquinone by enzyme tyrosinase Dopaquinpne converted to melanin  TYR gene codes for enzyme tyrosinase Recessive allele on gene TYR that causes a lack of enzyme tyrosinase or inactive tyrosinae No tyrosinase enzyme, tyrosine cannot be converted to melanin  Homo allele

sickle cell anemia

Sickle cell anemia HBB gene Haemoglobin  Frequent infections and anaemia Abnormal haemoglobin in red blood cells  B-globin polypeptide is coded by gene HBB  Abnormal allele on gene HBB produces diff sequence of alleles Base sequence is altered - amino acid substitution GAG replaced by GTG CTC replaced bt CAC Altered sequence, abnormal B-globin, Glu replaced by Val Shape of red blood cells affected and unable to transport oxygen  Hetero carrier, homo abnormal

haemophilia

Haemophilia 

• F8 gene

• Factor VIII

• Not normal blood clotting 

1. Sex linked gene F8 

2. Gene F8 codes for factor VIII protein 

3. Abnormal alleles less production of factor vii or no production viii

4. No factor viii = prevented normal blood clotting 

5. Males will have condition, females can be heterozygous and be a carrier

Heterozygous female carrier, homo male

huntingtons diesease

Huntington's disease

• HTT gene 

• Huntington

• Lose ability to walk talk and think 

1. HTT gene codes for huntingtin protein 

2. Abnormal HTT gene 

3. Repeating triplet sequence 

4. Abnormal is dominant over normal

Heterozygous

Homozygous abnormal alle

gibberelin stem elongation

• Le dominant allelefunctional enzyme active gibberelin

• le reccessive allele codes for non functioning enzyme inactive