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What does the notation Rr mean to geneticists?

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What does the notation Rr mean to geneticists?

A-heterozygous alleles.

B-homozygous alleles.

C-dominant alleles.

D-recessive alleles.

Punnett square showing a genetic cross between two heterozygotes (Aa), showing a 25% chance of offspring having a recessive homozygous condition (aa).

The correct answer is A. heterozygous alleles.

Genes are sequences of DNA that are found on chromosomes. An allele can be defined as an alternative form of a gene. For example, a flower may have purple or white petals. One allele would be for the purple color and the other allele for the white color.

In Mendelian genetics, the principles of dominance and recessiveness were discovered through experiments that were conducted on pea plants. Where traits follow Mendelian rules they can be either dominant or recessive.

A dominant allele is a trait that is always visible phenotypically. This means that it is always expressed when inherited by progeny. A recessive allele is only sometimes expressed in the phenotype (outward physical appearance of the genotype).

Chromosomes occur in pairs known as homologs. Each member of a homologous pair has the same genes at the same position on the chromosome. The reason we have homologs  is that we inherit one from our mother and one from our father. These two alleles may be the same or different.

One may be dominant and one recessive, or both dominant or both recessive. If an allele is dominant it is indicated with an uppercase letter, while if it is recessive, it is indicated by a lowercase letter.

Dominance and recessiveness

If you inherit an allele that is dominant, then you will show the trait regardless of if you only inherit it from your mother or father. If you inherit a recessive allele then you will only display the trait if you inherit this same allele from both of your parents.

A dominant allele essentially “dominates” and is always seen. A recessive allele is hidden by the effects of a dominant allele if you only inherit it from one parent. This is why recessive traits are often less common in a population than dominant traits.

The concepts of recessiveness and dominance were discovered by Gregor Mendel. Mendel did experiments using pea plants, which he bred for several generations. The genetics of what was happening was unknown to Mendel as chromosomes and genes had not been discovered yet.

Mendel, however, realized that there was some trait or factor that was clearly passed from parents to offspring. He discovered that sometimes the trait was seen in the offspring of parents, but at other times it was only seen in the grandchildren of the parents.

For example, he discovered that purple flower color was always seen in the next generation if even one of the parental plants had purple flowers.

Crossing a plant with white flowers with a plant with purple flowers did not produce equal numbers of white and purple flowers in the offspring. In fact, Mendel found that only fewer of the young plants would have white flowers, compared with purple flowers.

This finding was because the purple, R was a dominant allele while the white, r, was a recessive allele. It was the genotypes of the parents that influenced what traits were inherited and how they were inherited.

Homozygous and heterozygous

Alleles that are inherited from parents can either be the same or they can be different. If both alleles are dominant or both alleles are recessive then the resulting genotype is described as homozygous. If one allele is dominant and the other allele is recessive, then the genotype is known as heterozygous.

An example of a heterozygous genotype then is Rr while a homozygous genotype could be either RR or rr. If two parents are heterozygotes then there is a chance that ¼ of the offspring can be the homozygote recessive form.

This is something that Mendel found. If two pea plants that had heterozygous purple flowers were crossed, then ¼ of their progeny would have white flowers.

The other progeny would have purple flowers. Furthermore, ¼ of the offspring would be homozygous purple and ½ would be heterozygous purple.

A plant which is a heterozygote for purple flowers when crossed with a plant that is homozygous for white flowers would have progeny in which ½ were homozygotes for white flowers and 1/2 were homozygotes for purple flowers.

At the same time, two pea plants that have white flowers will only produce offspring with white flowers. This is because the white color is only expressed in the homozygous form since it is a recessive allele.

Mendel’s laws

Mendel discovered two important laws which allow us to predict proportions of genotypes and phenotypes in the progeny of parents.

The law of segregation states that the alleles separate independently during the meiosis that occurs in the germ cells that become the gametes. This means that an allele can end up in any of the gametes and one of the parent’s alleles will be present.

The second important law is the law of independent assortment. This means that the alleles are inherited independently of each other. In other words, the selection of one trait is not dependent on the selection of another trait.

The relevance of Mendelian genetics

Although many conditions are caused by traits that are inherited in a non-mendelian fashion, there are some diseases that do follow Mendelian rules.

Certain deadly diseases such as Tay-Sachs disease, cystic fibrosis, Huntington’s disease, and sickle cell anemia are inherited in a Mendelian way. This means that one can predict the likelihood of an illness showing up in the children based on the genotype of the parents.

Since these illnesses follow rules of dominance and recessiveness it means that it is possible, in some cases where the disease is caused by a recessive allele, for parents to be carrying the allele but not to be sick.

Cystic fibrosis, Tay-Sachs disease, and sickle cell anemia are all caused by recessive alleles and thus parents can be asymptomatic carriers. Huntington’s disease, though, is different. This is an illness that is caused by a dominant allele.


H Chial (2008). What can Gregor Mendel’s pea plants tell us about human disease? Single gene disorders, like Huntington’s disease and cystic fibrosis, actually follow Mendelian inheritance patterns. Nature Education.
Editors of Encyclopedia Britannica (2018). Mendelism. Retrieved from Encyclopedia Britannica.
RL Dorit, WF Walker, RD Barnes (1991). Zoology. Philadelphia: USA, Saunders College Publishing.
RH Raven, RF Evert, SE Eichhorn (1987). Biology of plants, 4th edition. New York: USA, Worth Publishers.
C Rye, R Wise, V Jurukovski, J DeSaix, J Choi, Y Avissar (2017). Biology. Houston: USA, Rice University.

What does the notation Rr mean to geneticists? - lifeder

What does the notation Rr mean to geneticists? – lifeder – What does the notation Rr mean to geneticists? Genes are sequences of DNA that are found on chromosomes. An allele can be defined as an alternative form of a gene. For example, a flower may have purple or white petals.What does the notation TT mean to geneticists? answer choices . two dominant alleles. at least one dominant allele. two recessive alleles. one dominant and one recessive allele. Rr and Rr. Rr and RR. Rr and rr. RR and rr. Tags: Question 16 . SURVEY . 30 seconds . Q. A trait that seems to disappear. answer choices . alleles.What does the notation rr mean to geneticists. what does the notation rr mean to geneticists?… Answer. Mathematics, 24.06.2019 16:50. 20m to 21m what is the percentage change… Answer. Mathematics, 24.06.2019 16:50. Describe the relationship between the area and the perimeter of two squares with a length of 2.5 and 5.

Genetics & Adaptations | Genetics Quiz – Quizizz – What does the notation TT mean to geneticists? A. Two dominant alleles B. Heterozygous C. At least one dominant allele D. One dominant and one recessive allele Is the answer A? Science. 1. White skin (W) is dominant over yellow skin (w) in chickens.simple Mendelian genetics…right-handed is the dominant allele (R), left-handed is recessive (r). you can figure it out using a Punnett square.What does the notation Rr mean to geneticists? heterozygous alleles homozygous alleles dominant alleles recessive alleles The notation RR means Heterozygous alleles to geneticists.

Genetics & Adaptations | Genetics Quiz - Quizizz

Which of michelangelo's sculptures is a metaphor for – That a person is heterozygous for a certain trait. Rr=heterozygous and RR= homozygous. You can remember this because Hetero= different and homo= same Virtual Teaching Assistant: Jared M.An individual who carries two copies of the same allele (i.e. RR or rr) is called a homozygote (homo = same, zygote = embryo). Homozygotes produce genoctypially identical offspring when allowed to self-fertilize. There are dominant homozygotes (i.e. RR individuals) and recessive homozygotes (i.e. rr individuals). An individual who carries two different alleles (i.e. Rr) is a heterozygote5. What does the notation TT mean to geneticists? 6. A clone is an organism that is _____. 7. The sex cells produced by meiosis have _____ (the) number of chromosomes as the parent cells. 8. What is the probability of producing a tall pea plant from a genetic cross between two hybrid tall pea plants? 9.

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اتبع الأميبا على Twitter (amoebasisters) و Facebook! ماذا snapdragons والطول البشري ، والرقبة
الدجاج في القواسم المشتركة؟ حسنا هم بسهولة تم تحديدها على أنها سمات غير مندلية. من غير المنديليين ،
نحن نقصد ذلك ، وراثيا ، هم كسر القواعد! انهم لا يتبعون Mendelian العادية
حكم أن وجود أليل مهيمن يعني السمة المهيمنة سوف تظهر. تذكر في موقعنا
الفيديو خنزير غينيا ، وجود أليل المهيمن — ممثلة من قبل H — يعني خنزير غينيا
شعر؟ فقط إذا لم يكن هناك حاضر مهيمن ، النمط الوراثي من سمو ، سيكون هناك أصلع
خنزير غينيا؟ هذه سمة مندلية. لكن ما سنقوم بتغطيته هو متى
الصفات غير مندلية ولا تتبع تلك القواعد الأساسية. دعونا نبدأ من قبل
نباتات أنف العجل. نعترف أنه عندما سمعنا هذه الكلمة ، كنا نظن أنها كانت حقا
نوع مذهل من المخلوقات. حسنا انهم مذهله لكنهم زهور. لذلك … أنا لا أعرف … هذا
ليس بالضبط ما تصوره. في أنف العجل الوراثة ، يمكن أن يكون هناك 3 أنماط ظاهرية. أحمر.
أبيض. أو شيء ما بينهما — وردي! انها يدعى الهيمنة غير المكتملة. في غير مكتمل
الهيمنة ، الأليل المهيمن ليس بالكامل مع الأليل المتنحية هو حولها.
حتى إذا عبرت زهرة حمراء (RR) وزهرة بيضاء (مكتوبة rr) ، يمكنك الحصول على الأطفال
هذا هو Rr. ولكن على خلاف الصفة المندلية ، إذا هيمنة غير مكتملة ، حيث أن أليل R
لا يتم التعبير عنه تمامًا عند وجود r. اذن Rr في هذه الحالة الوردي! إذا كنت عبور اثنين
الزهور الوردية (Rr) ، كما هو موضح في هذا Punnett مربع هنا … يمكنك الحصول على ذرية
أحمر أو أبيض أو وردي. الهيمنة غير كاملة مختلف عن السوم. سيادة مشتركة — مثل
زميل العمل — أن الإصلاح "المشترك" يجب تجعلك تفكر معا. يعملون معا.
الأليلات ، وهذا هو. لهذا السبب ، نحن ترغب في استخدام أحرف مختلفة تماما. في
بعض السلالات من الدجاج ، وهناك codominance تنطوي على اللون. الق نظرة على هذا Punnett
ميدان. إذا كنت تعبر دجاجة سوداء — ممثلة بواسطة BB —- والدجاج الأبيض —- ممثلا
by WW —— جميع ذرية هنا BW. دجاج BW كلاهما أبيض وأسود. مبقع!
انظر ، كلا السمات تظهر — هذا هو الجوهر من الازدواج. وأنت تعرف ، ما هو أكثر من ذلك
رائع من الدجاج الأرقط؟ حسنا ما عدا بالنسبة لتلك الدجاج bantam silkie … بواسطة
الطريقة ، ستجد أن العديد من الناس يستخدمون مختلف التنسيق من أجل الهيمنة غير الكاملة والسودانية.
بعض الناس يحبون استخدام أحرف مختلفة تماما للهيمنة غير المكتملة — بعض الناس
لا. بعض الناس يفضلون أيضا القيام الأسس مع codominance —- بعض الناس لا. التنسيق
جانبا عند حل المربعات بونت ، منذ ذلك الحين نجد أن هذا يمكن أن يغير حقا الفصول الدراسية ل
الفصول الدراسية ، والمفهوم الحقيقي هو أنه في غير مكتمل الهيمنة — واحد من الأليل ليس مهيمنًا تمامًا
على الجانب الآخر لذلك ترى ما يقرب من "في بين "النمط الظاهري. إذا سادسة ، لا
الأليل هو المسيطر على الآخر ، لذلك كليهما وأعرب alleles.Height هو رائع.
في عائلتنا المباشرة ، يعد Pinky أطول من بتونيا. أمنا أطول أيضا من بتونيا.
كيف يحدث هذا؟ ليس هناك واحد فقط ارتفاع الجين. هناك الكثير من الجينات التي
تحديد طولك. ما أعنيه بذلك هو أنه ليس لديك فقط زوج من الأليلات ،
مثل AA أو Aa أو aa التي ترمز إلى طولك. انها أشبه شخص لديه نمط وراثي
من AABbCcDD وغيرها لتحديد ارتفاع في نهاية المطاف. وترث أليل واحد لكل من
ارتفاع الجينات — من كل والد. كل هذا تعمل الجينات معا لتحديد طولك.
لون بشرتك يتحدد أيضا من قبل الكثيرين الجينات تماما مثل طولك. تسمى هذه
السمات متعددة الجينات. بولي يعني الكثير — حتى "العديد" جينات الترميز لخاصية واحدة هو ما هو متعدد الجينات
يعني. بالمناسبة ، كل من الطول ولون الجلد يمكن أن تتأثر بالعوامل البيئية
كذلك. تغذية تنمو حتى يمكن أن تؤثر على حياتك ارتفاع مثلما تنفق الكثير من الوقت في
الشمس يمكن أن تؤثر على لون بشرتك. ومع ذلك، هذا لا يغير الوراثة لهذه السمات
أخيراً ، أكثر نريد أن نتحدث عنها ، قشوة. Epistasis هو عندما جينة واحدة حقا
يعتمد على جين آخر ليتم التعبير عنه. أعني ، إنه يعتمد بالفعل على هذا الجين الآخر.
لذلك دعونا اختيار حيوان مثل … طيب … على … .llama. دعونا نقول أن هذا اللاما لديه المهيمن
الأليل باء الذي يعني صوفها سيكون أسود. يعني BB أو Bb أنه سيكون له صوف أسود
ودعنا نقول أنه إذا كان اللاما لديه زوج من الأليلات المتنحية — ب ب — سيكون لها اللون البني
صوف. الآن ماذا لو كان هناك جين آخر — جينات إبيستاتي — التي تسيطر على ما إذا كان
حتى سيتم التعبير عن الصباغ في اللاما الصوف في المقام الأول؟ اللاما يمكن أن يكون
نمط جيني من CC أو Cc أو cc لهذا الاستاتيكي الجينات. ومع ذلك ، إذا كان اللاما لديه النمط الوراثي
سم مكعب ، فإنه لن يسمح للجين الآخر للصوف لون حتى أعربت عن ذلك. منذ ذلك الحين لدينا اثنين
جينات هنا — الجين لون الصوف و جينات إستشارية —- هذا يدعو إلى المفضلة لدينا
16 ديهيدريد مربع. إذا لاحظت في هذا معبر ثنائي الهجين اثنين من اللوالب المتغايرة
(BbCc و BbCc) ، BB و Bb عادة إعطاء اللاما السوداء و BB تعطي عادة
اللاما البني في جميع الحالات ما عدا الاستاتيكي الجين الموروث هو سم مكعب. إذا كان اللاما لديه سم مكعب
في التركيب الوراثي ، ثم الجين الخاص بلون الصوف لا يعبر عنه واللاما هو البينو.
هذا يعني أنه لا يتم التعبير عن أي صبغة الكل. مثيرة للاهتمام للغاية. هناك العديد من الآخرين
غير المندلين السمات — لدينا فيديو آخر على الأليلات المتعددة وفيديو مرتبط بالجنس
الصفات — التي هي أيضا غير مندلية. انها نوع من السحر لنرى ما يمكن أن يحدث
مع قواطع هذه القاعدة. شيء أخير. ضع في اعتبارك أنه عند حل المشكلة في
علم الوراثة ، لا تريد أن تفترض فقط غير مندلية ما لم يتم تزويدك بالمعلومات
أو القرائن في المشكلة التي قد تكون. حسنا هذا كل شيء من أجل الأخوات الأميبا و
نحن نذكركم بأن تبقى فضولي! .

Ep. 49 "How To Roll Your R's and Tongue Trills" – Voice Lessons To The World – Hi everybody! My name is Justin Stoney
and I'm the founder of New York Vocal Coaching
here in New York City.
Welcome to episode 49 of
Voice Lessons To The World. The show where we want
to help you guys as singers by answering your questions
from all over the world. And I'll give you a chance
to ask questions later. But our question for
this week comes from Anthony C. in
West Haven, Connecticut. And Anthony writes, "Dear Justin,
I would love to learn how to roll my R's. But I can't do it. Can you show me
how to do it?" Yes, Anthony. I think I can and this
is a great question because we do need to be able to roll our R's
and do tongue trills often when we sing
and when we speak. Now most of you probably
know what this is but let's talk about what is a
tongue trill or a rolled R is. Where the front of your
tongue comes up and meets your hard palate
or your alveolar ridge you get a sort of
[Demonstrates sound] sound. Now it's not the back, it's the
buzzing against your hard palate. Now why do we
even need this? For one thing we need this
if we're going to be doing some classical repertoire that uses
Italian or maybe Spanish. Or if we want to speak
those languages we need to roll our R's and also it makes for
a great vocal exercise. So those of you that
already know how to do this hang in there for the end,
because we're going to do an exercise together where you get a
chance to work some tongue trills. They're really great
for the voice. And then finally is there
any sound that you guys really don't want to be
able to make? We know that on this show
we're going to cover every sound that there is
out there, over time. And we want to be versatile
with our voices. We want to not
have limitations. We don't want to have
sounds that we can't do. So if you want to be
able to do a tongue trill now's your chance
to be able to do it. Now some people think
that they can't do a tongue trill. And most of the time
this is not true. I will admit though there's
a genetic issue sometimes for people with
tongue trills. There are some people that
just will not be able to do the trill. But here's the two things that,
genetically speaking, if you can do it you're
going to be able to do the trill. Here's what they are… Number one, you need to
be able to lift your tongue like this. In the front it's got to lift up and
touch the hard palate. That's the first thing. Second thing though, this is the
one that's harder for some people, is you have to be able
to curl your tongue. The sides of the tongue
have to be able to come up. Or else the trill won't work so
if you can curl your tongue in a sort of u-shape
in the middle and the sides and you can lift it
you will be able to do the trill, alright. Even if you can't now
we're going to work together right now to be
able to do it. So here are some
steps for you guys to be able to do a
tongue trill, okay. First I'm gonna tell
you a couple common ways that have helped
people get it in the past. One is repeating words that
kind of have the sound of it. Like, say the word "butter". If we say, butter butter butter butter
butter butter butter butter butter it kind of puts the tongue
in that trill kind of place. Try that out say butter a
bunch of times. Here we go… That was nice. So you feel that
butter butter butter. Right. Now another thing is
to kind of use a Scottish accent. Just say for me, Scotland is great
[Scottish accent] Okay try that out. That's right. Scotland is great
[Scottish accent] That was nice, good. Good job. Alright, so that sound "guh guh"
that is going to start the tongue trilling. So that's kind of just a
few ways that people have talked about in the past. What I'd like to do for
you guys today is talk about how it's not just
the front of the tongue we need to address
to get this trill right. But, the whole tongue. I'm going to show you
what I mean. So first of all,
the front. Here's what we
have to do with the front. First of all we need the
jaw and mouth relaxed. And then the tip
is going to come up, not to meet the teeth. If you're meeting the teeth
you're too far forward for the trill. We're trying for the
alveolar ridge. Whoa. That is a part of
the hard palate. It's a little further
back from the teeth., It's not the gums,
it's not the teeth, it's a little further
back on the hard palate. That's your alveolar ridge,
that's where the trill is going to take place. So that's one thing
you really have to know. The thing is that tip
of the tongue has to be loose. If the tip is tight you will
never do the trill. That is what is flapping. So if you tighten that guy
it's not going to be able to flap. So really, when you're
trying these trills you've got to keep the
front super relaxed and touching the right place. Now that's just the front. Most people have trouble
because they're only thinking about the front when
they're doing the trill. But now we need to
know about the sides and then also the back. So here's the sides. The sides, as I say,
they have to be able to curl up. You have to curl your
tongue on the sides. First of all,
meet the teeth. Let's try touching the
sides of the tongue to the teeth. probably the molars. Alright, okay. So you're going to
meet the sides of the teeth. This is not how to do it
but the first step to doing it. When you do the actual
trill it's going to be inside the teeth. But first meet the teeth
with the sides of the tongue. That's good. Okay so if you've got that
now just think about a few of these sounds
that you may have heard. This is kind of a retroflex tongue,
this "err" sound. We have a curl and a
pull back of the tongue. You may have heard this with the
announcer Tom Brokaw. NBC Nightly News
with Tom Brokaw. And it has that kind
of curl to the sides. Or Austin Powers, Dr. evil,
he does the "I'm still hip, I'm still cool,
taka-taka-taka-taka" That sort of "huh" sound
of the sides of the tongue, you've got to engage that
when you're doing [rolls tongue] or else that won't
stabilize things. So that's what you've
got to do with the sides. Now finally the back. The back is another
thing that people miss. We can't have the
back shoving down and we can't have it
totally loose. It has to have a little
bit of upward activity. One way to find this is
with a sort of velociraptor sound. Try this crazy thing for me. Try a… [Demonstrates sound] Okay here you go… Very scary, good. One more time… [Demonstrates sound] That was great. So we have the back
of the tongue also engaged. That's one of the great things. If you're trying that
D or R sound in the front and then you
engage in the back, you're also
curling the sides. That is how you're going to be
able to find the trill again. Most people are neglecting
the lift of the back and the lift of the sides
when they're doing the trill. So I hope that that helps you guys
to start finding the mechanics of all the aspects
of the tongue, so that you can
get the trill. One more bonus
tip for you. If you try another
trill like a lip trill, some people can trick
themselves into doing it by feeding their tongue
through that trill and using the one trill
to influence the other. That's just another nice
trick for you to try as you're experimenting. So that's how
to do it. Let's fast forward to
say that you figured that out
after some practice and now also those
folks who already know how to do this we're going
to put it to an exercise. We're going to go up and
down with a tongue trill. This helps with your
breath support, it helps with
your flexibility, and with
your registration. Because we're making
an even sound, even volume, even production
all across the range. So here's what
it's going to be. 1-3-5-8-5-3-1 Guys down here… And ladies up here… And here we go
together with the trill. Alright. Awesome stuff. So now you know
a little bit more about how to do that trill,
how to get the mechanics right. And then also you
can use it in an exercise to help build your voice. So Anthony and all,
I hope that's been helpful for you guys
today as singers. If you've got questions that you'd
like to see us answer on the show, you can send an email to,
[email protected] And so we just
encourage you, don't lose that joy,
don't lose that passion, don't let people tell you
that you can't sing you and I both
know that's just not true. Get with a great
voice teacher in your area or if you guys are in
New York City or you want to
Skype with one of our staff you can visit, And if you guys
like these videos I just encourage you to
download our free app for iPad, iPhone, and hopefully
more in the future. So many great tips, videos,
articles, more stuff to help you guys
grow as singers. So check out that free
app and you can also visit I'm Justin Stoney. We'll see you next time. ♬ .