Simple Genetic Cross Example Using Punnett Squares

Learn more about Punnet Squares here: • Punnett Square Basics ...
Learn more about Alleles here: • Homozygous vs Heterozy...
Learn more about Genotypes and Phenotypes here:
• Genotype vs Phenotype ...
Let’s solve a simple genetic cross using a Punnett square.
In rabbits, coat color is determined by a single gene with two alleles: uppercase B (brown coat) and lowercase b (white coat). A homozygous dominant brown-coated rabbit (BB) is crossed with a homozygous recessive white-coated rabbit (bb). Determine the possible genotypes and phenotypes of their offspring.
To start, let’s set up our Punnett square. We will put the brown-coated rabbit alleles across the top. Both uppercase B.
And the white-coated rabbit on the side. Both lowercase b.
Now we match up the alleles in their corresponding squares. In this case, every square gets one big B and one little b.
So these are the possible outcomes, and the question asked for the possible genotypes and phenotypes.
Genotypes are the alleles, which are 100% heterozygous, big B and little b.
The phenotype refers to the expression of the genes. Given that there is only one genotype, we only have one phenotype, brown-coated rabbits.

[@Joseph-fp1pm]

Never learnt this before, now watching an hour before my exam 😅 wish me luck ig

[@2MC]

You got this!

[@Joseph-fp1pm]

@@2MC aayy I passed my ged science with this in it!! Thanks man

[@MoreTrenMoreMen69]

same right now. my laptop broke a few days ago and haven’t been able to get it fixed so this is gonna have to be my studying😂

[@justme-yq6od]

How did it go?

[@Joseph-fp1pm]

@@justme-yq6od been a good few months now so I don't remember anything specific. I passed with 170 something out of 200 points for the exam with this in I believe

[@Alex73736]

You explained it better than the book lol. Thank you!

[@victorcoste-qp6wm]

Excellent explanation. I would say however (and this is just the way I was taught) that if you have 2 of the same letters, like BB and bb, I would only cross B with b in the Punnet square. It makes the ratios easier to find, and also generally simplifies the whole process.
I love this explanation tho! Keep on making good content! 👍

[@Notmarianaroblox]

Tysm! It helped me for my exam tomorrow!

[@Dreamai.]

bro u teach better than my low quality not paid enough teacher fr

[@fadenovajruexxx1197]

I hope this gets me ready for my test

[@jocelyn9058]

great video, super clear

[@Aleh_idk]

LO EXPLICASTE GENIAL GRACIAS

[@user-re4iv6ny1p]

Omg thank u soo , much u are a hero ☺️

[@BartSimpski]

Thanks bro my test is tomorrow

[@2MC]

Good luck!

[@CamilaAsto]

lol I’m here bc my teacher called in me and said exactly this and I was confused by now I know THANK YOU

[@BrightFubara]

Powerful❤

[@i.love.ohcean]

I LOVE YOU SO MUCHHHH

[@Diamondsigmaspaceb]

Why did i see this right before my genetics test lol

[@Mia23-ib5gi]

What will be the genotype and phenotype ratio ?

[@poojasinghal4580]

Thanks alot❤

[@2MC]

You're welcome.

[@SolethuSaki]

Tommorow I will be writing practical task about genetics oww God

[@gamingwithsrikanth5064]

They asked us this question as 4 marks

[@joshlaurencec.zacarias4808]

Could you do it in 3rd generation/F3?

[@AdrenalineDemon30]

Thanks 😢

[@2MC]

You're welcome

[@dragon-ksp]

Then if two rabbits with Bb gene get crossed, there is 25% chance that their child will have bb gene

[@user-ju9pq8fc9l]

What happens when it is Rr X Rr

[@user-ik3gf5oi4q]

Then we get RR Rr Rr Rr
Which means genotype is 1:2:1
And phenotype is 3:1

[@Ilikepanchos-sg9hq]

Was this complete dominance???

[@SusanaDalmacio-kc7od]

yong black and white

[@topefromyt1501]

whats thr ratio?

[@2MC]

1

[@macmckulis7440]

It is not that simple, lol this is like kindergarten of genetics.

[@aiyegbogbonolamide8645]

Just learning this few hours to my exam 😂🤡

[@xuehua4574]

Genotypes are BB=0% Bb=100% and bb=0%

[@Cup1dz.xqz_]

….totally failed my test tdy