L7 notes ; genes & inheritance

Question 1

KARYOTYPE

dark bands vs light bands

Answer 1

appearance & no. of chromosomes in a cell

dark bands; HETEROCHROMATIN ; tightly packed
chromosome material of different density, usually greater where the activity of the genes has been modified or suppressed.

light bands ; EUCHROMATIN ; lightly packed

• made of DNA,RNA , & protein
• enriched in genes & is often under ACTIVE TRANSCRIPTION
• most active part of genome

Question 2

GENOME

Answer 2

contains genetic material of an organism

Question 3

meoitic NON DISJUNCTION

Answer 3

where pairs of (homologous) chromosomes do not separate properly

Question 4

meiosis quick recap process

Answer 4

pro, met, ana, telo PHASE x2 ;

Question 5

aneuploidy

Answer 5

abnormal no. of chromosomes (usually 1)
trisomy - additional chromosome
monosomy- loss of chromosome

Question 6

homologous vs non homologous chromosomes

Answer 6

H- contain alleles for same gene

NH- contain alleles for different genes

Question 7

translocation def
2 diffrent types ;
do not confuse with ;

Answer 7

chromosome abnormality
exchange of DNA between NON-HOMOLOGOUS chromosomes

balanced- exchange of genetic material is equal
clinically normal & fully functioning

unbalanced - exchange of genetic material is NOT EQUAL
this can cause lots of problems

DO NOT CONFUSE WITH MEOITIC RECOMBINATION during meiosis - occurs between HOMOLOGOUS chromosomes

Question 8

dosage compensation

Answer 8

process by which organisms equalise the expression of genes between members of different biological sexes

i.e. means equalising the gene expression of particular genes between different organisms

EG in females one X chromosome is silenced
this means both males and females have only one active X chromosomes

Question 9

barr body

Answer 9

inactive X chromosome can be seen on slide

barr body is what its called

Question 10

age card to do

Answer 10

now

Question 11

most WHAT genes are expressed from both maternal & [paternal are called ;

Answer 11

autosomal genes

Question 12

one method of silencing alleles we don’t want

Answer 12

METHYLATION

Question 13

MENDELIAN TRAITS assumption

Answer 13

• 1 allele is dominant over another

- chromosomes separate/segregate into paternal & maternal alleles

Question 14

carrier

Answer 14

an organism that carries a dominant and recessive allele but does not show the trait or phenotype for the recessive allele – it just carries it

Question 15

pedigree analysis diagrams

• male
• female
• mating
• children
• affected
• heterozygous
• deceased

Answer 15

male ; square (4 sides 4 letters)
female; circle 
mating; horizontal line 
children; vertical line 
affected; coloured in 
HZ- ; contain  different alleles for a certain gene
deceased; line through square/circle

Question 16

x linked recessive;

who is more affected?

Answer 16

males

they only contain one X chromosome

Question 17

non MEDELIAN inheritance

Answer 17

• Co-dominance ; when one allele is not dominant over another
• incomplete dominance; when the trait of the dominant isn’t completely shown over the trait if the recessive allele
  i. e. both alleles contribute to the phenotype
• polygenic - when lots of genes are NB towards a particular trait etc

-multifactorial - when environmental factors influence genes also swell as genetics itself e.g. smoking
ie genes & EF can together result in disease