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Course: High school biology - NGSS > Unit 1
Lesson 2: Genes, proteins, and cellsGenes, proteins, and cells
All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells. Created by Khan Academy.
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- 1. In the video, she said different genes code for different proteins and that different combinations of proteins determine the function of a cell. She also said all cells are made up of the same genes, but wouldn't that mean they're also made up of the same proteins which means they have the same function? I know cells obviously have different functions but I'm confused as to how all cells are made from the same genes but can still have different functions.
2. Since we inherit 2 sets of genes for a trait, one from each parent, then how does the dominant trait show over the recessive? Is there something special about the proteins that the genes in dominant traits code for?(7 votes)- 1. From what I understand, the same DNA molecule has multiple genes within it, each then codes for a different protein. So if the DNA is a library, every cell has the same library which all have the same cookbook and each cell uses a different book from that library to cook a different meal. Thus, the cells are made of the same DNA but different genes. I might be wrong though, this is just from what I understand after watching it too.
2. The dominant trait is just dominant apparently, the way its coded is that it overrides the recessive genes. I'm not very sure about it though so I would check with a teacher or maybe another science course to double check it.(9 votes)
- Hi guys~ I am going to 9th grade next year and I chose the science class for biology. May I know do 9th-grade biology need these? It's a bit hard for me(7 votes)
- This is high school biology, so yes you would be doing some of this, but this course is multilevel. Meaning this is about the four years of high school combined. You should definitely do it, as parts of it will be part of 9th grade, just don't be too hard on yourself if you have trouble. Some parts will be harder than 9th grade biology. Have fun!(4 votes)
- How are genes made?(2 votes)
- Genes are made from the parents x and y chromosomes. Using a Punnett Square, people can determine what gene they may get. For example, say X (dominant trait) is tall and x (recessive trait) is small stature. XX means two dominant Xx or xX is still dominant because the dominant trait takes over the recessive one. If there is xx, that is the only way the recessive one can occur. Hope this helps.(12 votes)
- Where does RNA come in?(5 votes)
- There are many different kinds of RNA, but RNA plays a crucial role in making proteins.(5 votes)
- i still don't understand(5 votes)
- Who are you actually? You don't sound like Sal? That voice sounds like a female. Anyway, you could used Genes, proteins and cells to create offsprings right?(4 votes)
- Idk who is her but I like her voice.
In fact cells and genes are used like that naturally. When conception occurs the egg cell and sperm cell each with half of the respective parent's chromosomes(strands of dna containing genes), offspring is ''created''. That also happens artificially as long as they have a receptacle to conceive the embryo. However proteins itself are not able to produce offspring, they serve to specific functions rather than creating a new being. Proteins dont have dna, they were just synthesized by the amino acids encoded from the dna's gene.(1 vote)
- can i do NGSS even if my state doesn't have it. Is it advanced ? Becuase I was doing it and just realized I'm doing NGSS even though Texas doesn't have it(3 votes)
- what is gene 1 and 2?(3 votes)
- What does it mean by Beta? Like is it a type of species or what? And does it have to do with DNA? I heard that you can have dominant genes too. That could happen(2 votes)
- It sounds like Beta fish but is actually Betta fish which is just a kind of fish(3 votes)
- Why does a person have genes from different people in there their family.(3 votes)
Video transcript
- [Instructor] So when I was younger, around seven or eight years old, I used to have a beta fish named Bob, and he happened to be a blue-colored fish. Now, I've always wondered
how he got his color. So for example, were
his parents also blue? Does he have any siblings that were blue? So today, let's try to
answer in simple terms how Bob gets his blue color. And we'll start by defining genes. Genes. What are genes? Well, genes are basic hereditary units that are well, first of all, they are passed down
from parent to offspring. So I'll write passed
down parent to offspring. And they also contain information about an organism's traits. Contain info about an organism's traits. So it would only make sense that since Bob is a blue-colored fish,
that he must have a parent or ancestor who is also blue-colored. Now, a single kind of gene can
have many different versions, and we call these versions alleles. Alleles. And these are just different
variations of a single gene. So for example, there may be a gene that provides information
about beta fish coloration. So let me draw an arrow from
Bob to, we'll say, color gene. And one allele of this gene may
lead to a blue-colored fish. So I'll write here blue color. And another allele may
lead to green coloration. And I'll write here, next
to blue color, green color. But physically, what are genes, exactly? Well, genes are part of DNA
or deoxyribonucleic acid. And I know, it's a really big word. So let me write it out for us. DNA. Deoxyribonucleic acid. DNA. So DNA is a macromolecule, or a really big and complex molecule. So when you hear macro, just
think big or complex molecule. And you can also think of
DNA like a giant cookbook of genetic information,
because that's what it is. It is a cookbook of genetic information. So here is a close-up sketch of DNA. And what I'm showing
here is that DNA consists of subunits called nucleotides. Nucleotides. And these are represented
by As, Ts, Cs, and Gs. Now genes are like the individual recipes. You can think of them as the recipes found inside your DNA cookbook. So they are specific
segments of nucleotides within the long DNA molecule. So a gene could be from here to here. And we think of this as a recipe. But what do these gene
recipes make anyways? Well, many genes encode proteins, which are made of long sequences or chains of amino acids. So, I'll write here under proteins that proteins are made
of amino acid chains. And genes provide instructions for how to create these chains. So thinking back to how
genes are like recipes because each gene has a different set of quote-unquote,
"ingredients", or in this case, a different nucleotide sequence, different genes would therefore
encode different proteins. So proteins in this example, if you want to continue
on with this analogy, proteins would be like
the finished products of your recipes. Remember how I mentioned that alleles are different versions of a specific gene? Well, different alleles have
different nucleotide sequences and are therefore likely to
also encode different proteins. So I'll write under
here, different alleles, and draw an arrow to different proteins. So different genes and different alleles can give us different proteins. So of blue fish like Bob,
likely has a distinct allele that encodes proteins, which
give him his natural blue color or his natural blue shade. Now, an organism has many different genes, which means an organism has the capacity to produce many different
kinds of proteins. And proteins serve all kinds of functions, some of which include
growth, sending messages, oh, also catalyzing chemical reactions, if you have heard of enzymes before. So, I'll write catalyzing
chemical reactions and providing structure. Ultimately, it's the activity of these different kinds of proteins that help determine an
organism's physical traits, just like how proteins can determine the color of Bob the beta fish. Now, you might be wondering too, what genes do in the big picture. For example, not all of the
cells in Bob the beta fish function in the same way, right? You could say that there
are different types of cells that perform specific functions. And this is known as cell specialization. So cell specialization is when
different cells specialize in different functions. And each type of specialized cell contains a unique combination of proteins that give the cell its
specialized function within an organism. So I'll write here that
cell specialization comes from unique combos of proteins. And it's important to note that every cell in an organism
contains the same genes. So going back to Bob here, we can say that all his cells contain the same DNA and genetic information, whether it's on his tail or in his eye, but what makes their functions different is which subset of genes are expressed or used to build proteins
in the different cell types. So, I'll write here, all of
the cells in Bob the beta fish have the same DNA and genes, just different protein combinations. So today, we learned about
genes which are passed down from parent to offspring, just like how Bob the blue
beta fish got his color, and they contain information
about organisms' traits. So genes are parts of longer DNA molecules and they consist of specific
segments of nucleotide bases. So thinking back to our cookbook
and recipe analogy, right? Genes can encode all kinds
of different proteins. And it's this unique set of proteins within each cell that gives
the cell its specific function within the organism. As we talked about with Bob the beta fish, and all of the cells in Bob
having the same DNA and genes, just different proteins.