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A Beginner's Guide to Punnett Squares

6445 ratings | 1024741 views
Paul Andersen introduces the Punnett Square as a a powerful tool in genetic analysis. He tries to address major misconceptions that students have when use a Punnett Square. He gives a number of examples of monohybrid crosses and one example of a dihybrid cross. The square is a simple tool that uses the outcome of meiosis to determine possible offspring in a cross. Intro Music Atribution Title: I4dsong_loop_main.wav Artist: CosmicD Link to sound: http://www.freesound.org/people/CosmicD/sounds/72556/ Creative Commons Atribution License
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Text Comments (745)
yasmeen algalham (23 days ago)
this is not for beginers this is for experts
ringpop103 (1 month ago)
What a legend.
Clumsy Hammy (1 month ago)
thhis guy is the worst teacher ever you stupid donkey
Nathan Fontanilla (1 month ago)
Shout out to the AP bio kids 2018
Biruk Obama (1 month ago)
bruhhh my final's tmr
Kyla Marie Garcia (1 month ago)
Thank u for this u saved me a big time
Emma Garcia-Navarro (1 month ago)
Did anyone get the punnett square for the last example? I'm getting four squares but he said that's too much?
Clark Monteron (1 month ago)
Why you wont put some genotefic ratio i need to know but its ok i learn some! Thanks
jennifer alger (2 months ago)
So many u tube videos are confusing. This one is not!
TheSpiritedDrifterVlog (2 months ago)
You’ve been helping me in College Biology. Thank you so much! I subbed.
Annissa Naranjo (2 months ago)
my dad
Jack Christl (2 months ago)
Morph Games (2 months ago)
Great video man, thanks for helping me pass biology!
funny tubes (2 months ago)
Really helpful video
BronzeSpaceComet (3 months ago)
Hey super helpful for my test tomorrow! So if anyone here who's good at this stuff reads this could you just confirm my answer for the question he leaves us with? Thanks! So I'm assuming the answer here is the Punnett square would be 4 by 1, because for the RrYy each character there are two possible alleles and 2x2 is 4 possibilities, but for the rryy, it could only give an rr and a yy and nothing else so the only possibility that parent could give is rryy. Also just to make sure I really got this down I'll go a step further - if you were to complete the Punnett Square, you would have one RrYy (heterozygous dominant for both), one Rryy (heterozygous for the first, homozygous recessive for second), one rrYy (homozygous recessive for the first, heterozygous for second), and one rryy (homozygous recessive for both). So there would be a 1:1:1:1 ratio for this dihybrid cross. And nowhere will you be seeing homozygous dominant for either trait because at least one recessive allele will always be contributed if I'm correct. Thank you again and please let me know what I did right/wrong, and correct me if I'm wrong anywhere!
Tahzib islam Yafi (28 days ago)
BronzeSpaceComet absolutely correct, nothing wrong here
Colin McLeod (3 months ago)
I stopped as soon as you referred to yourself as Mr.
King Invincible (3 months ago)
Thanks a lot..........you saved my life.............
Neha (3 months ago)
You are awesome sir!!
iM A bAnaNA bAnaNA (3 months ago)
9:30 was like ROUND AND YELLOW
Vyshakh Vathielil (3 months ago)
9:24 Every time he says round, he sounds like Owen Wilson when he says "Wow".
Iza Yanna (3 months ago)
Someone please help me. I dont understand why its 1:1 shouldnt it be 4:4?
Clarissa S (3 months ago)
and round and yellow
A O (3 months ago)
Bozeman saving student since 2011
AidenRxm (4 months ago)
Linds14 (4 months ago)
I have a test on this tomorrow and my bitch ass teacher said to us to learn stuff that she has not taught us. If that doesn’t show that she’s the shittiest teacher alive I don’t know what does
Thank you so much, it really help me and good thing is i passed the test
Nexus Romanova (4 months ago)
Thanks! :)
Faaiz Alam (4 months ago)
Thank you brother
Sgt. Anarchy (4 months ago)
11:06 three of the Fuck Phenotypes
Farah Khan (4 months ago)
WAOOOOO I took bio class in 2012, I had ALMOOOOOST forgotten everything, such a great REVISION. GOD BLESS YOU <3
Kellie Holland (4 months ago)
You are amazing. You have officially saved me
ChampChris (4 months ago)
"And this one right here, it's gonna be round, and it's gonna be yellow, so it's gonna be round and yellow,  and this one you can see, it's gonna be round and yellow, and round and yellow, and round and yellow, and round and yellow, and round and yellow, and round and yellow, and round and yellow, and round and yellow. So in other words, nine are going to be round and yellow."
paola la diabla (4 months ago)
round and yellow round and yellow round and yellOW ROUND AND YELLOW ROUND AND yellOH ROUND AND YELLOW
Gerald Geñoso (4 months ago)
Can u be my teacher?
amara shah (4 months ago)
Quiz in three periods 😩
Aman karn (4 months ago)
Thank you sir
Federico (4 months ago)
Can someone please tell me what's the genotype for the 9:3:3:1 ratio phenotype?
jory 0 (4 months ago)
Federico yes
Happy (4 months ago)
9:3:3:1 is the phenotypic ratio right?
THANK YOU SO MUCH FOR DOING THIS!! YOU EXPLAIN IT MUCH BETTER THAN MY TEACHER DOES AND NOW I FINALLY UNDERSTAND THE DIHYBRID CROSSES!! I have a test about it tommorrow but now I don't have a bad feeling anymore! Thanks a bunch!
Rashed Alzghoul (4 months ago)
LuciferHasPinkSparklyWings yo same and I am in 9 th grade 😂first I was like fuck it bought now I think I can pass it
Holly Duncan (4 months ago)
lovely shari (5 months ago)
Wow thank you so much 🙌🏼 I understand
Christine joseph (5 months ago)
Thank u so much really thank u
Evolution (5 months ago)
kill me now
Vishakha Salvi (5 months ago)
Nice explanation. Douts has been cleared By watching this video. Thanks for this video
XxHandsomeMagicXx (5 months ago)
Wow! this was extremely helpful
Jyoti Ghosh (5 months ago)
Sir in the homologous chromosomes the two chromosomes of a pair are considered or the chromatids if a single chromosome are considered to be similar?
Jyoti Ghosh (5 months ago)
Sir genes are the specific sequences of nucleotides in a chromosome so where are the alleles present?
Jyoti Ghosh (5 months ago)
Mr. Anderson I am quite confused regarding what is trait and an allele. In case of sex linked inheritance we have the recessive Gene of haemophilia or any other disease on the x chromosome which leads to the appearance of a trait. So what is the relation between the gene, the allele and the trait in this case.
Piston Cat (5 months ago)
cool thx very helpful
BBadonkaTrunk HTK (5 months ago)
That lil p is the size of his dick
Rashed Alzghoul (4 months ago)
BBadonkaTrunk HTK bruh lol 😂😂😂
Jacob Charo (6 months ago)
Everyone's here trying to get ready for a test but im already out of school so this is just me being a nerd. I'm here trying to learn about snake genetics :)
Shekinah Curry (6 months ago)
Does the order of the ratio matter?
Weird7thgrader ಠ_ಠ (6 months ago)
middle school............sigh......................
Arush Ramteke (6 months ago)
So does the capital (dominant) gamete always come first while writing the outcome?
Mojo Does Rainbow (6 months ago)
My comment
Kirsten Yu (6 months ago)
My hero!! Thank you Mr. Andersen! You're the absolute best <3
James Myers (7 months ago)
I am an older student in an art major curriculum retaking biology because... not really sure. Maybe the school thought it might help me mix egg tempura colors. It's been a running firefight to maintain the grade average I need and more of a challenge than I thought I'd have. But I just want to say that quite a few of the cell division, reproduction and genetic topics were so much easier coming from your videos than the McGraw Hill textbook. You've got a real gift for instruction. Owe you big time and thanks.
Jason W (7 months ago)
11:05 three of the fuck phenotypes that are yellow and wrinkled. Yea fuck biology.
Shobhit Pandey (7 months ago)
Awesome thanks for your video!😁❤
Dragonquest is best (7 months ago)
Kris The Canadian (7 months ago)
dihybrid cross with 2 sex linked genes?
JWG Fishies (7 months ago)
Good stuff
Raymond Matthew (8 months ago)
gracias :D
Lily Bailey (8 months ago)
So with the Dihybrid cross, you would put the parents' alleles into a Monohybrid cross and put the results into the Dihybrid one, right?
Nirvana Nagi (8 months ago)
You are a fucking GOD
oofBrendan (9 months ago)
Kit Cooper (9 months ago)
Thank you. This guy helps sooo many people. I wonder how many people passed a test cause of him.
nell 100 (9 months ago)
but color blindness does not occur in women i guess??
It does occur, if say frequency of defective allele on X chromosome in a gene pool would be 0.01 than 0.01 males would be affected, as for the females 0.01 x 0.01 = 0.0001 would be affected - in females we would see that color blindness will occur 100 times less frequent than in males.
R0b3rt (9 months ago)
Thanks !
Suman Preet Suman Preet (10 months ago)
how to make trihybrid cross table it's so confusing
It is much easier to use forked line method in this case: https://www.youtube.com/watch?v=cYqZrxwINDY
RINN MB (10 months ago)
James Ruz (11 months ago)
Who here has this as their assignment in Highschool?
Mae Tabbu (11 months ago)
thank you!!!
subhangi mukherjee (1 year ago)
parent RrYy *rryy the punnett Square would be4*2 it would be RY,Yr, yR , ry and on the other side of the square will be ry,ry
Manuel De La Cruz (1 year ago)
thank you very much Bozeman I have bio final tomorrow and this really helped me.
Caughtlighght (1 year ago)
This video made me have peas for dinner
Rodevina Guevara (1 year ago)
answer to the last question in the video please. Thank you.
min min for the win win
Akshay gorana (1 year ago)
recombination does not takes place in dihybrid cross
If genes on the same chromosome - it does and it would effect calculations depending on distance in sentimorgans.
Akshay gorana (1 year ago)
No U (1 year ago)
After looking at the comments on a lot of Bozeman Bio videos it seems like I'm one of the lucky few to have a good AP Bio teacher
J 117 (1 year ago)
I really learned alot in this video and hope this helps me for the STAAR Test i have next week, thumbs up for this video and wish me luck guys and have a fantastic day😁.
Swathika Tamil (1 year ago)
i understood the topic ☺
Laura Beatrice (1 year ago)
That was VERY helpful, thanks! You explained everything very clearly!
Argelia Chavez (1 year ago)
Amazing. This helped alooot!
thank you for the first time I understand!!!!!!!!
Lauren Linett (1 year ago)
got a test thursday!
Jacob Proctor (1 year ago)
You basically just summed up a week of my class that now makes sense to me. Thanks, test tomorrow.
Myda Baig (1 year ago)
When no video is there to help. You're there. Unparallel videos. THANK YOU SO MUCH
Stephano Paraskeva (1 year ago)
What was the phenotypic ratio and the genotypic ratio for the dihybridcross?
Northern Wolf (1 year ago)
caroline sunuwar (1 year ago)
why do chi squares have to have heterozygous pairs
Nicole Angela (1 year ago)
This is actually helpful, thanks
Skrillers (1 year ago)
Hope Ruek (1 year ago)
Thank you thank you. Never learned this in high school (I home schooled myself lol) and now in college my professor breezed over it thinking we all knew it already. Life saver!!
Josh Johnson (1 year ago)
Could someone tell me why big R and little r (Rr) is not a possible combination in his explanation between 8:00 and 8:30?? he used every combos except that one
No he also did not list YY, yy, Yy, RR, rr Rr because gamets have only one allele of each gene. and Rr - is 2 alleles of the same gene.
Mabel Abraham (1 year ago)
Thank you so much
trancers planets (1 year ago)
keep it up...!!
Sal Hamad (1 year ago)
What about Tri-hybrid Crosses. Those are the only ones i am struggling on.
It is much easier to use forked line method in this case: https://www.youtube.com/watch?v=cYqZrxwINDY
prasoon tripathi (1 year ago)
really helped me a lot for my exams
Uswa Sajid (1 year ago)
how make tetra hybrid cross if make cross between AACCRRpp x aaccrrPP
It is much easier to use forked line method in this case: https://www.youtube.com/watch?v=cYqZrxwINDY

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