Fundamentals of Genetics - Video Tutorials & Practice Problems

Genetics Basics

Hi in this video, we're gonna be talking about the fundamentals of genetics. So the very first thing that you talk about is just genetics basis. And so most of this is going to be review from an intro bio course that you may have taken. But I want to review it here just to make sure you're refreshed on this material and everybody's on the same page. So D. N. A. Is of course going to be the funnel unit of genetics. So what should we know about DNA before we move forward to more complicated things, we need to know that DNA is made up of four bases. We call these bases nucleotides those basic, there's gonna be A. T. C. And G. Here are the fancy names for them. Remember that there's going to be proper pairings. So certain bases pair with other bases. So the person who discovered that was charged off and he made up the rules of what the pairings were. And so his rules say that a pair with T. And C. Pairs with G. And then these pairings are done because these pairings are preferred because of the number of hydrogen bonds they can make. So A. And T. There's two hydrogen bonds and CNG there's three hydrogen bonds. And so these pairings they pair together. Now when these parents occur they're going to make the strand complementary. So what does that mean? It means that if we have a pairing here, which is A. And T. C. And G. C. And G. T. And A. That this side is going to be complementary to this side, meaning that these bonds are going to be the ones that form because the opposite pair. So if it's an A. On one side there's always going to be a T. On the other. So that means that they're complementary. And then the D. N. A. Strand is two strands and the proper energy formation of that's a double helix. So D. N. A. It has these four bases. These bases form A. And T. C. And G. And it's a double helix. Again like I said things that you've probably heard about before but just want to refresh the material here. Now D. N. A. We care about it in genetics because DNA contains genes, water genes, genes are just gonna be stretches of DNA. So A D. N. A sequence that has some type of information on it. And that information is used to create a protein. And proteins are what allow us to function. So a gene is going to be a stretch of D. N. A. It's going to encode for a protein. It's gonna tell ourselves how to create a protein. And then that protein will go on to do have some type of function that keeps us alive or gives an appearance or does something in the body. Now jeans also come with regulatory elements. So it's not just the gene that encodes for the information but the body has to regulate when those genes are expressed. So in terms of regulatory elements, these regulatory elements are going to control whether or not the gene is expressed and when it is and where it is whether in a certain cell type or in a certain region of the body. So we have D. N. A. It's consists of these four bases. They pair a certain way D. N. A. Has genes. The genes are controlled through regulatory elements. And then one of the last things you need to know about this section about D. N. A. Specifically is about alleles. And pretty much what an allele is is because jeans come in different forms. Now. One of the most confusing parts of genetics for students is one of the very first confusing parts of it is understand what khalil is. You hear the word of lille and you hear the word gene you pretty much got jean down like you've heard gene enough in your life and you know what a gene is. It's a stretch of DNA that codes for a protein. But what in the crap isn't Alil, it's like this weird term that people get really confused about. And Alil is just a gene variant. Right? So we have a gene for hair color and that's it's a stretch of D. N. A. And it encodes for hair color. And Alil is going to determine whether that hair color is blond, whether it's brown, whether it's black, whether it's red, whether it's a mixture of strawberry blonde. So those alleles are the different forms that that gene can come in. So a gene is going to be hair color. A gene will not be blond hair color or black hair color. A gene will be hair color and then the color that it is blonde, black, whatever those are the alleles. And so in deployed cells deployed another fancy term. So in humans, we have two alleles per gene. And this combination of alleles will tell us what we look like or what the gene does. So in the case of hair color, the combination of these two alleles will determine whether our hair is blonde, black brown, what red, whatever color it's going to be. So make sure you understand that Angelil is just a gene variant because people get this confused all the time and you're gonna have a really difficult time in genetics if you do not know the difference between gene and Alil, So make sure you get that now. So here we have an example showing a leal's versus jean. So we have our two chromosomes, right? Because we're deployed. So we have two copies of every gene. So we have gene A. Gene B and jean, C. Now, gene A. Is the blue jean, jean B is the green gene and gene C. Is the red gene. But you can see that the a leal's represent different variants. So this Khalil is like a dark blue where this khalil is a light blue. Now it's still the blue gene just different variants. This one is green and so this is the same allele even on different chromosomes. And that can totally happen. And then we have our red which we have a dark red and a light red. So make sure you completely understand the difference between alleles and jeans or else you're gonna be really confused this whole semester. So we start off with D. N. A. So that's what we've been talking about so far. But in genetics were not only concerned with DNA, were also concerned with what that DNA encodes for what the gene makes and the gene makes the protein. So how do we go from D. N. A. To protein? Well an intermediary, you've probably talked about this and there are two main steps. There's the transcription and the translation step. So the transcription step turns D. N. A. Into our N. A. Um And then the messenger RNA is used to create protein. But there are other types of RNA. Which we will talk about if you don't necessarily know them right now, that's okay. So if we get so transcription takes DNA to RNA. And then the second step, translation takes that M. RNA to proteins. So this is really important. We're gonna spend some time talking about it. You're probably familiar with at least the basics of this and this class will go into a little bit more detail. Um So we know that D. N. A. Does not encode a protein in a 1 to 1 manner. It's not that all A nucleotides produce all the same type of protein. Remember there's you have to decode it. So the D. N. A. To R. N. A. Is 1 to 1 but the RNA to proteins is 3 to 1. In the case that we have this thing called a code on and a code on is a collection of three nucleotides that we have A C. T. For instance this is gonna be a code on and this code on here will encode for one amino acid which is gonna be the building block to build proteins. So we start with D. N. A. We turn it to M. R. N. A. And then every three are 10 a.m. This is M. RNA. So it's you. Um every three nucleotides for an R. N. A. Is going to make up one amino acid. So here we have an example of what this is. So we start out with our RNA. Remember RNA is gonna be used to create protein and translation. Um And so we have our three nucleotides here and encodes for one coat on. And this code on creates the amino acid Alani. Then we have our second coat on and this code on creates the amino acid three inning. And this keeps going code on by code on until we stop and together all of these amino acids are going to create one protein. So I hope this wasn't too fast for you. Most of this should be pretty much all of this should be a review from an intro bio class about what D. N. A. Is made up of how it all comes together and then how we take genes from D. N. A. And turn them into proteins, these basic steps. So we will go over each one of these things and much more detail in future videos and future chapters. But just wanted to give you a refresher because you probably haven't thought about this in a little while. And so we just need to get back into thinking about biology and specifically genetics. But the one thing you really take anything away from this video is the difference between jean and ALil because you don't want to get those confused in a genetics course. So with that, let's move on.

Chromosomal Fundamentals

Okay. So we talked about DNA, let's now talk about chromosomes, chromosomes can have many different types of formations or they come in different types of formations. The one you're going to hear about a lot of homologous chromosomes. These are just pairs. They're just pairs. You know, you have two chromosomes. They're homologous because they they're paired together. Now deployed another term. You're gonna hear two in and these are gonna be organisms that have homologous chromosomes. They have a chromosome pair. Then you have hap Lloyd which has one less chromosome. So instead of having a pair it just has the one chromosome copy and these are really important terms, we're gonna hit them so many times Just to make sure you get it. You understand this deployed is sometimes written as two in because two chromosomes um and half lawyers written as in because of the one chromosome. Now, chromosomes are so important for genetics and inheritance because the chromosomal theory of inheritance states that traits come from genes on chromosome. So without chromosomes you're not going to inherit anything. The jeans sit on the chromosomes and you inherit the chromosomes that are on those jeans and the chromosomes that are inherited are passed through what's known as gametes. And these are sex sells. So these are sperm an egg. If we're talking about humans now, how do we get gametes? Well, this is through the process of my osmosis. This produces gametes. What you do is in deployed individuals that's going to be humans. You take two in cells. You take a deployed cell and over time through a bunch of different steps, which we'll talk about in a lot of great detail um you get four hap Lloyd cells and those half Lloyd cells then go on to fuse or combined with other hap Lloyd cells to create a deployed organism. In our case these hap Lloyd cells are sperm and egg and when they come together they create a deployed zygote. Um don't worry about, you know, necessarily getting all of that down. Hopefully this is all review. But if it's not we're gonna talk about a lot of this in a lot more detail of the future. Then you have mitosis which we're not going to talk about a lot in this class. We're mainly going to focus on my Asus but mitosis does still exist. We'll talk about it briefly and that's the process of creating somatic cells. Somatic cells are every cell that isn't a gammy. So that's your skin cells, your eye cells, your brain cells, your toe cells literally all the cells that aren't sperm and egg and humans. And so this takes deployed cells turns to in cells into more two in cells. So with diocesan chromosomes, what you get is you start with a deployed organism and undergoes mitosis. You end up with half Lloyd. So sort of one copy of each chromosome. So these are the homologous chromosomes and you end up with one copy after mitosis in each cell and then through fertilizations of the combining of the sperm and the egg that will create another deployed organism. So, like I said, we'll go over these in a lot more details. These are just basic review fundamentals. So now let's turn the page.

Descriptive Genetics

Okay, so now let's talk about a few terms that we use to describe things in genetics. So the first is on an individual level. So we can say that an individual has a certain genotype, that genotype, what we're referring to is the genotype is going to be the set of alleles. So these are going to be the actual alleles for a given trait. So if we want to know color, for instance, hair color, eye color, then the genotype is going to be the alleles which alleles you have. The phenotype is different, doesn't necessarily care what it is. You have, it just looks at what you look like. So if we're looking at hair color that would be blonde, it would be brown, It could be black. Um any of the read any of these hair colors. That's the phenotype genotype, you can't actually see it. You have to actually know what it is you have. And then um genes present themselves in many different um as many different types of traits you have morphological traits. These are going to things that affect the appearance, affect skin color, feather color, height or you know, anything like that size, then you have physiological traits and that's going to affect the ability of an organism to function properly. So that could be something like the shape and function of the lungs can help the physiological aspect of taking in air and breathing. Um and then you have behavioral traits and these are going to affect the way organisms respond to its environment. It's hard to think of for humans, even though it does exist, but I think it's more easy to think about different, you know, mating dances that birds or other organisms do you read about the male does some kind of fancy mating dance to attract the female? Those are actually behavioral traits that can be inherited through genetics. So if we're just looking here, you can see the phenotype is yellow or green and the genotype is here. So these refer to different types of alleles with the upper case letter representing angelil that's dominant. So something you're going to see if it's there. Um and then the lower case letter is going to refer to something that's recessive, which you'll only see if the dominant is absent. Don't worry if your don't necessarily remember dominant recessive, we'll go over this in a lot more detail. But I just kind of wanted to get you to understand phenotype is just what you see, genotype is going to be, you know what you can't see but what we're going to spend a whole semester learning how to actually figure out. And then there are three divisions of genetics. These are transmissions genetics. This is going to be genetics that studies the studies inheritance essentially studies the ability to pass traits on to the next generation, then you have molecular genetics and this studies the ability or gene activity at the molecular level. So examples of this are DNA replication or transcription or translation, these are molecular genetic events. And then finally you have population genetics and these are going to be studies of genes in terms of the entire population. So if we take the entire population of the United States, what are traits and what are the different, you know, genetics of people in the United States compared to people in Australia or people in kenya? Um, and these types of population genetics we're going to talk about towards the very end of this semester, but we'll hit all three of these. Um, so with that overview, let's now turn the page.

In a diploid cell, the number of alleles is the same as the number of genes.

• A. True
• B. False

What is an allele?

• A. A nucleotide variant
• B. Different variants of a gene
• C. Proteins
• D. Codon

The chromosomal theory of inheritance states that….

• A. Traits come from the mixing of fluids from two parents
• B. Traits come from only chromosomes found in the egg cell
• C. Traits come from genes on chromosomes
• D. Traits comes from complementary DNA strands

Which one of the following is NOT a division of Genetics?

• A. Transmission genetics
• B. Molecular genetics
• C. Breeding genetics
• D. Population genetics