Topic 3: Genetics

Proteins

________ can be separated according to charge.

● IAIB

________ causes the glycoprotein to be altered by the addition of both N- acetyl- galactosamine and galactose.

Humans

________ have 223- 8 million different ways to place chromosomes.

Cytokinesis

________ occurs, forming 4 haploid gametes.

Nondisjunction

________ and Down syndrome: Occurs during anaphase I and results in a chromosome excess or deficiency in a gamete.

thuringiensis

Analysing risks to monarch butterflies of Bt corn: ● Gene transferred to corn from Bacillus ________ that codes for Bt toxin.

● Anaphase I

________: o Homologous pairs are separated.

Karyograms

________: A(n) ________ shows the chromosomes of an organism in homologous pairs of decreasing length.

antibiotic resistance

● Do not contain genetic information that is useful for basic life processes but contain the information for ________, for example.

Huntingtons disease

________: Caused by the dominant allele of the HTT gene on chromosome 4.

identical organisms

Cloning: Production of genetically ________ is called cloning.

Metaphase I

________: Spindle microtubules move homologous pairs to equator of the cell.

Separation

________: Segregation of alleles into different nuclei.

Punnett grids

________: Parent generation consists of two pure breeds (two of the same allele)

Genetic diseases

________ due to recessive alleles: ● Most ________ are caused by a recessive allele.

Meiosis

________ and genetic variation: Crossing over and random orientation promotes genetic variation.

Mutation

________: New alleles are formed by ________.

O Totipotent

________- Can form any cell type, as well as extra- embryonic (placental) tissue (e.g.

DNA

________ are all negatively charged but are too long to move through the gel so are broken up into smaller fragments by restriction endonucleases.

Plasmids

________: ● Eukaryotes dont have ________.

Sex linkage

________: When inheritance patterns are different in males and females, it is presumable that the inheritable feature is located on a sex chromosome.

Prophase II

________: Chromosomes, which still consist of two chromatids, condense and become visible.

adult animals

Cloning ________ using differentiated cells: ● Cloning by somatic cell nuclear transfer: o Adult cells are taken from the udder of a sheep.

Alleles

________ are the various specific forms of a gene.

thymidine

Since tritiated ________ contains the radioactive isotope of hydrogen, tritium, the DNA produced by DNA replication would be radioactively labelled.

Digestive processes

________ are inhibited because the pancreatic duct is usually blocked by the mucus so digestive enzymes can not reach the small intestine.

Sickle cell anaemia

● Sickle cell anaemia is caused by a base substitution in the Hb gene that codes for alpha-globin polypeptide

● The body cannot replenish red blood cells at the rate at which they die, so there is a shortage of red blood cells

anaemia

Genome

● Whole of the genetic information of an organism

Plasmids

● Eukaryotes dont have plasmids

Measuring the length of DNA molecules using Cairns technique by autoradiography

● Cell were grown for two generations in a culture medium containing tritiated thymidine

Eukaryotic DNA

● Is associated with histone proteins, which are globular proteins

Differences between chromosomes

● Chromosomes supercoil during mitosis/meiosis and can be seen then

Homologous chromosomes

● Carry the same sequence of genes but not necessarily the same alleles of those genes

Genome sizes

● Genome sizes are correlated with the complexity of the organism but arent directly proportional

Haploid nuclei

● Haploid nuclei have one chromosome of each pair

Diploid nuclei

● Diploid nuclei have pairs of homologous chromosomes

Chromosome numbers

● The number of chromosomes is a characteristic feature of members of a species

Sex determination

● X and Y-chromosomes determine sex

Karyograms

● A karyogram shows the chromosomes of an organism in homologous pairs of decreasing length

Meiosis and sexual life cycles

● The halving of the chromosome number allows a sexual life cycle with fusion of gametes

Replication of DNA before meiosis

● DNA is replicated during the interphase before meiosis so that all chromosomes consist of two sister chromatids

Random orientation of bivalents

● Random orientation is caused by the random positioning of the bivalents during meiosis I

Halving the chromosome number

● In meiosis I the centromere does not divide and whole chromosomes move to opposite poles

● Chorionic villus sampling

sampling tool obtains cells from the chorionic villi, a membrane from which the placenta develops

● Telophase II

Chromatids reach opposite poles

Meiosis and genetic variation

● Crossing over and random orientation promotes genetic variation

● Random orientation of bivalents

o 2n number of random orientations of bivalents, where ‘n is the number of chromosomes possessed by a haploid nucleus of an organism

● Crossing over

o Allows linked genes to be reshuffled to produce new combinations, called recombinants

● Fertilization and genetic variation

o Fusion of gametes is random

Nondisjunction and Down syndrome

● Occurs during anaphase I and results in a chromosome excess or deficiency in a gamete

Gametes

● Gametes are haploid so contain one allele of each gene

Zygotes

● Zygotes have two alleles of each gene

Separation

● Segregation of alleles into different nuclei

● If PP, all gametes would receive a P. If Pp, 50% of gametes would receive P and 50% would receive p. Dominant, recessive and co-dominant alleles

● Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects

Ck

Red flowers

CwCk

Pink flowers

Punnett grids

● Parent generation consists of two pure breeds (two of the same allele)

ABO blood groups

● IA is dominant because it codes for an active protein

Genetic diseases due to recessive alleles

● Most genetic diseases are caused by a recessive allele

Other causes of genetic diseases

● Red-green colorblindness and haemophilia are examples of sex-linked diseases

Cystic fibrosis

● Cystic fibrosis is caused by the recessive allele of the CFTR gene, on chromosome 7

Huntingtons disease

● Caused by the dominant allele of the HTT gene on chromosome 4

Sex linkage

● When inheritance patterns are different in males and females, it is presumable that the inheritable feature is located on a sex chromosome

Red-green colorblindness

● Genes are located on the chromosome

Haemophilia

● Stems from an inability to make clotting Factor VIII

Causes of mutation

● High-energy radiation can be mutagenic as it can cause chemical changes to DNA

DNA profiling

● DNA is obtained from a known individual