SECTION 7 - BIO Flashcards by Unknown Unknown

Define genotype?

the alleles present in a cell (sylabus: the genetic constitution of an organism

How well did you know this?

Not at all

Perfectly

define phenotype

the observable characteristics due to alleles being expressed (sylabus: the phenotype is the expression of this genetic constitution and its interaction with the environment)

How well did you know this?

Not at all

Perfectly

define locus

position of a gene on a chromosome

How well did you know this?

Not at all

Perfectly

chromatid

when DNA in a chromosome replicates the 2 copies are held together by a centromere and are called chromatids.

How well did you know this?

Not at all

Perfectly

Co-dominant

Both alleles are expressed in the phenotype if they are both present. they both produce functional, but diff, proteins. (neither one is recessive)

How well did you know this?

Not at all

Perfectly

alleles

different forms of the same gene

How well did you know this?

Not at all

Perfectly

dominant

allele expressed even if heterozygous. produces a function protein

How well did you know this?

Not at all

Perfectly

recessive

allele expressed only if homozygous. caused by a mutation resulting in the allele producing a non-functional protein.

How well did you know this?

Not at all

Perfectly

Homologous pair

pair of chromosomes in a diploid cell. contain same genes but possibly different alleles. form bivalents during meiosis.

How well did you know this?

Not at all

Perfectly

monohybrid inheritance

inheritance involving a single gene with more than 1 allele

https://merchanttaylorsschools-my.sharepoint.com/:w:/g/personal/tofoma_merchanttaylors_com/EVGU2ffcoFRHuQWVNNogNnsB6G9YF0YDXC-a7jYkTof70Q?e=n9rvv9

How well did you know this?

Not at all

Perfectly

dihybrid inheritance

inheritance involving 2 genes at different loci on different chromosomes.
https://merchanttaylorsschools-my.sharepoint.com/:w:/g/personal/tofoma_merchanttaylors_com/ETwrMZY9WZhNjm0a9V4N4UgBdAxUC54gmBnNJ1O-falBTw?e=KEzXqm

How well did you know this?

Not at all

Perfectly

CODOMINANCE.

both alleles will be expressed in the phenotype
neither is recessive
there are 3 possible phenotypes:
1) homozygous of one allele
2) homozygous of the other allele
3) heterozygous (has both dominat alellesl)

eg, R=red fur
W = white fur

RR = red fur
WW = white fur

RW= pink fur

How well did you know this?

Not at all

Perfectly

some genes have more than 2 what? which can lead to what? and give an example?

alleles, leading to the expression of many diff proteins in the phenptype. example: Blood type.
https://merchanttaylorsschools-my.sharepoint.com/:w:/g/personal/tofoma_merchanttaylors_com/EQuHHp7gasFLqQzdJ9x9-VkBLcQrdm0BxLxEEd3K4AkgkA?e=sBoZcP

How well did you know this?

Not at all

Perfectly

MULTIPLE ALLELES

GENES HAVING MORE THAN 2 ALLELES.

How well did you know this?

Not at all

Perfectly

SEX-LINKAGE

A GENE THAT IS FOUND ON A SEX CHROMOSOME is said to be ‘sex-linked’

How well did you know this?

Not at all

Perfectly

most genes on sex chromosomes are carried by which chromosome? and why?

most genes on sex chromosomes are carried by the X chromosome. because males only have one X chromosome, they often only have 1 allele for sex-linked genes, because they only have 1 copy of the gene, hence they express the characterisitc of this allele, even if its recessive which means males are much more likely to show recessive phenotypes for sex-linked genes.

How well did you know this?

Not at all

Perfectly

the gene which determines if you have haemophilia is found on which chromosome, making the disease ____

X chromosome, making haemophilia sex-linked

How well did you know this?

Not at all

Perfectly

haemohpilia is caused by which allele

the recessive allele

for the recessive haemophilia allele to be expressed, males require how many copies of it and why?

1, because males only have 1 x chromosome

CARRIER =….

some1 who has the faulty recessive allele but is heterozygous with a dominant allele present.

explain why males are much more likely to show recessive phenotypes for sex-linked genes? (refer to bothmales and femaels

females may be carriers
males require only 1 allele

what are autosomal genes?

genes that arent found on sex chromosomes

autosome

any chromosome that is not a sex chromosome (humans have 22 pairs of autosomes, and 1 pair of sex chromosomes)

genes on the same autosoome are said to be what?

linked

genes on the same autosome are said to be 'linked'. they will stay on the same chromosome during which process in meiosis 1, and offspring will inherit what. Except for which scenario will these 'linked' autosomal genes not stay on the same chromosome, and hence offspring wont inherit the alleles together?

during independent segregation in meisosis, and offspring wil inherit these alleles together. except for if they are separated during crossing over. (Linked autosomal genes will stay together on the same chromosome — except if they are separated during crossing over, hence The offspring might not inherit those alleles together anymore.) - (leading to a new combo of alleles in the offspring)

the closer together the 2 linked genes are on the same chromosome (the closer the autosomal genes are on the same chromosome), the what?

the less likely theyll be split by crossing over.

when 2 genes are linked (i.e close together on the same chromosome/autosome), are they separated or not, and what does this lead to in terms of the combonation of alleles prodcued?

they are not separated, hence you would get the same combo of alleles

linked genes

linked genes are genes that are close together on the same chromosome (i.e autosome)

(linking to flash 27), if 2 autosomes are linked, whats the outcome in terms of phenotypic ratio? (compared with the offspring of a normal dihybrid cross)

u wont get the phenotypic ratio you'd expect from the offspring of a normal dihybrid cross

what ratio do u get of the combo of allels in the offspring of a dihybrid cross where both parents are heterozygous.

9:3:3:1 ratio

ON THE CONTRAST OF FLASHY 30, WHATS THE RATIO U WOULD GET WITH AUTOSOMAL LINKAGE

3:1, BECAUSE THE 2 LINKED ALLELES ARE INHERITED TOGETHER. (as no separation cuz no crossing over)

AUTOSOMAL LINKGAE MEANS WHAT IN TERMS OF OFFSPRING HAVING THEIR PARENTS GENO AND PHENOTYPE.

autosomal linkage means a higher proportion of offspring will have their parents genotype and phenotype

define epistasis. how it works and give an eg,

the effect of one gene on another. the 2 genes interact so that one may be masked (prevented from being expressed) by another. https://merchanttaylorsschools-my.sharepoint.com/:w:/g/personal/tofoma_merchanttaylors_com/EdUuAbtRxmBGjpyNjto2XhcBZ40zPkrWRURO_BvTqg_Y2Q?e=JWcmKM

why can epistasis provide difficulties for genetic investigations?

because if the effect of one locus is altered/masked by effects at another locus, power to detect the first locus is reduced.

what is the chi-squared (X^2) test used for in the case of genetics and to observe/see what?

to compare the goodness of fit of observed phenotypic ratios with expected ratios. hence that means we could use it to see if there is a dihybrid cross with no linkage or whetehr the genes involved are linked.

in chi squared test in the case of genetics, why will you rarely get the expected phenotypic ratios?

random fertilisation of gametes epistasis small sample size

to see if the diff between the observed and expected outcomes is significant (i.e are other factors at play) we can use a chi-squared test. explain the whole test and outcome.

1) Find χ² (given in exam) 2) then compare χ² with the critical value (to find the critical value we need to know the degrees of freedom (which is the number of classes - 1), as we use the degrees of freedom to look up the critical value) 3) if the value of χ² exceeds or is equal to the critical value, the null hypothesis is rejected. (in the example of phenotypic ratios the null hypothesis is that there is no significant difference between the expected and observed phenotypic ratios) if we reject the null hypothesis this means that: there is less than 5% probability that the diff between the expected and observed phenotypic ratios is due to chance.(final outcome/statement that must be said in exam Q,)

species exist as how many populations?

one or more populations

define a population

a group of organisms of the same species occupying a particular species at a particular time that can potentially interbreed.

GENE POOL

THE COMPLETE RANGE OF ALLELES PRESENT IN A POPULATION

ALLELE FREQUENCY (GIVEN AS DECIMAL/%)

HOW OFTEN AN ALLELE OCCURS IN A POPULATION

the hardy-weinberg principle provides a mathematical model which predicts what?

that allele frequencies will not change from gen to gen.

give the 2 equations for the hardy weinberg principle

https://merchanttaylorsschools-my.sharepoint.com/:w:/g/personal/tofoma_merchanttaylors_com/ERUHvvvPsrNFvxIVUQGc7rcB8aSegfQqWIja4loEOEeU4Q?e=qGWwjF