Passing on information

Question 1

What is Genetics

Answer 1

-Genetics is the study of inherited variation

Question 2

Inheritance

Answer 2

◆ Clonal inheritance
● Genetic material must be copied then partitioned into daughter cells
◆ DNA replication
◆ Partitioning of copied material
-There are checkpoint that ensure fidelity G1( cell growth and damage), G2(Cell size and DNA replication)

Question 3

Mitosis

Answer 3

• Interphase: DNA is loosely pack with two copy of chromosome
• Prophase: DNA start to condense, Spindel structure develop form microtubules and attach to centrosome
• Metaphase: Microtubules attach to the centromere and pull it to the middle of the cell vertically
• Anaphase: Spindle pull centromere apart so each sister chromatids are pulled to the opposite side of the cell
• Telophase: forming two new cell via cytokinesis

Question 4

Genomes and Ploidy

Answer 4

-the number of Genomes are not all the same in different species
-Genome size is not dependent on organism size
Ploidy
Number of copies of the genome (denoted by n)
● Haploid (n), diploid (2n), triploid (3n), etc.
● Ploidy not necessarily static
◆ Lifecycle
◆ Somatic cells versus gametes
-Evolution

Question 5

Chromosomes

Answer 5

Structures that make up the genome
● Made up of genetic material (DNA or RNA)
● can be Circular or linear
-Have many Substructure ◆ Centromere, telomere, origins of replication, etc.
-Chromosome number varies between organism
- Genetic material can be found outside of chromosomes ◆ Plasmids ◆ Organelles (mitochondria and chloroplasts)

Question 6

Genes

Answer 6

Chromosome carry genes 
● Gene number varies between species
◆ Not correlated with genome size
 ◆ Not correlated with chromosome number
 Genes are present in almost all cells 
 Genes in all cells are almost always the same (antibody-producing cell)

Question 7

Genes, Alleles and DNA

Answer 7

• Genes may or may not encode for a protein(rRNA are not translated)
• Alleles are variation of a gene define by their locus
• Alleles have many possibility and the amount depend on the cell’s ploidy
• the function of protein produce by different alleles might differ from each other
• They can have repetition or gene family

Question 8

Genetic Transmission

Answer 8

Horizontal transmission : Clonal inheritance number of Ploidy unchanged
Vertical transmission for Mating Allows for exchange and assortment of genetic material

Question 9

Why is the amount of ploidy reduced during meiosis

Answer 9

Ploidy would double each mating if this doesn’t occur

Question 10

Meiosis

Answer 10

• During metaphase 1, homologous pair of chromosome pair up and aline with each other so after telophase 1, the daugther cell have two copy of the same chromatids
• division occur again to produce haploid daughter cell

Question 11

Genetic exchange results in new combinations of alleles

Answer 11

● Random Assortment of chromosomes

● Recombination (crossing over) between chromosomes, the location where this occur is called the chiasmata

Question 12

Errors in division

Answer 12

-Non-disjunction occurs in anaphase in meiosis 1 or 2. both homologous goes to the same pole

Question 13

Sex Determination

Answer 13

Many different mechanisms
● Environmental influenced (genetic mechanism)
◆ Reptile sex is determined by incubation temperature of eggs
● Genetic
◆ Ploidy
❖ Hymenoptera (bees) –females (workers and queen) are diploid (fertilized egg), drones are haploid (unfertilized egg)
◆ Ratio of autosomes to sex chromosomes ❖ Drosophila–XY system; female (X/A=1), male (X/A=0.5)
◆ Sex determining gene/chromosome ❖ Mammals –XY system; Y determines maleness ❖ Birds –ZW system; ZZ males and ZW females

Question 14

Heterogametic and homogametic

Answer 14

● Heterogametic -different sex chromosomes

● Homogametic -same sex chromosomes

Question 15

Chromosomes and Genes

Answer 15

◆ Genes are on chromosomes
● Chromosomes carry many genes
● The orientation of a gene is not necessarily the same as the genes around it
● The location of a gene on a chromosome is called a locus(pl. loci)
● Homologous chromosomes carry the same loci (genes) in the same order
-Diploid carry two copy of every gene, one in each of the homologous chromosome
-Some gene only have one copy (hemizygous)

Question 16

Segregation of Alleles

Answer 16

Mendel’s First Law

● Alleles will always segregate away from each other into gametes

Question 17

Multiple allele

Answer 17

● Diploids have two copies of every gene ◆ Carry one or two different alleles (A1A1or A2A2; A1A2)
● Genes can have more than two alleles when considered at the population level ◆ A1, A2, A3, A4, etc.
● Diploid individuals have only two of all possible alleles

Question 18

Sex linkage

Answer 18

● Some species have sex chromosomes
● Sex chromosomes carry genes just like autosomes
◆ Genes need not be related to sex determination or sexual differences
● Inheritance patterns will differ by sex
◆ Homogametic and heterogametic sexes will have different numbers of alleles
◆ Homogametic sexes carry two alleles and can be homozygous or heterozygous at a locus
◆ Heterogametic sexes carry one allele and are hemizygous at a locus

Question 19

Independent Assortment

Answer 19

Mendel’s Second Law
● Alleles of different genes will always assort independently from each other into gametes
● Independent assortment of chromosomes
Phenotypic ratio 9:3:3:1

Question 20

Recombination

Answer 20

◆ Recombination frequencies are a proxy for distance between two loci

• Map distance =100xnumber of recombinant/total progeny
• Homozygous gene have cis link(SY : sy>Sy: sY)
• heterozygous gene have trans link(Sy : sY>SY: sy )

Question 21

Test cross

Answer 21

◆ Cross to a homozygous recessive individual ◆ Test for linkage ◆ Phenotypic ratio not 1:1:1:1

Question 22

Mutations

Answer 22

◆ Mutations can occur anywhere in the genome (genetic material)
● Their effect on gene or genome function can vary:
◆ No effect (silent)
◆ Reduced or complete loss of function
◆ Gain or altered function

Question 23

Dominance/Recessivity

Answer 23

• One functional allele is sufficient to generate a wild type phenotype (dominant)
• One functional allele is not sufficient to generate a wild type phenotype (incomplete dominant)
• Both allele is sufficient to generate a wild type phenotype(codominant)

Question 24

Genetic Interaction

Answer 24

Organisms have many genes
● Some traits are controlled by one gene ◆ Monogenetic traits
● Many traits are controlled by more than one gene
● Some traits are controlled by many genes ◆ Polygenic traits
● Genes operate together to build traits ◆ Eg.Animal fur characteristics have many aspects
● Genetic interactions can affect inheritance patterns

Question 25

epistatic

Answer 25

when the effect of a allele is dependent on the presence or absence of mutations in one or more other genes

Question 26

How does mutation arise

Answer 26

Mutations in the genetic material can arise spontaneously or be induced ● Spontaneous -Replication errors ● Induced -Action of mutagens ◆ Failure to repair leads to inheritance of the mutation

Question 27

Where can mutation occur

Answer 27

Mutations can occur anywhere in the genome

Question 28

factor that influence the consequence of mutation

Answer 28

◆ Consequences of mutations depend on many factors ● Location in the genome ◆ Eg.Within functional units such as genes or outside ● Type of mutation –size and nature ◆ Eg.Base substitution, deletion, insertion, chromosomal rearrangement ● Somatic versus germ line ● No effect to lethality

Question 29

effect of mutation in the coding region of genes

Answer 29

◆ Changes may or may not affect the amino acid sequences of protein coding genes due to Degeneracy of the genetic code. ◆ Changes may or may not affect the structure or function of proteins

Question 30

Single nucleotide polymorphisms

Answer 30

Often referred to a point mutations ● Considering the effect of mutation in the coding region of genes ◆ Four different classes of point mutation ❖ Base substitution ◆ Silent -Change of nucleotide but no change in amino acid specified ◆ Missense - Change of nucleotide and change in amino acid specified ◆ Nonsense -production of a stop condon ❖ Base deletion or addition ◆ Frameshift

Question 31

effect of mutation in the non-coding region of genes

Answer 31

◆ Non-transcribed or transcribed but not translated ◆ Changes may or may not affect the timing of gene expression ◆ Changes may or may not affect the location of expression ◆ Changes may or may not affect the level of expression

Question 32

Insertions and deletions (Indels) mutation

Answer 32

● Mutations can be small or large ◆ One base pair to hundreds of kilobase pairs ● Mutations may change the reading frame ● Mutations can disrupt gene expression or regulation ● Mutations can fuse different genes together

Question 33

Chromosomal Mutations

Answer 33

Large deletions, inversions and translocations ● Mutations are generally large ● Mutations may disrupt gene expression, regulation or function ● Mutations can fuse different genes together

Question 34

Genetic Mutational Screens

Answer 34

Geneticists use induced mutations to identify genes that control traits ● Genetic screens