Chromosomes and genes (article) | Khan Academy (2024)

Review your understanding of chromosomes and genes in this free article aligned to NGSS standards.

Want to join the conversation?

Log in

  • victoria.gibson

    2 years agoPosted 2 years ago. Direct link to victoria.gibson's post “How many genes are in a c...”

    How many genes are in a cell?

    (25 votes)

    • Adonalsium

      2 years agoPosted 2 years ago. Direct link to Adonalsium's post “Around 50,000 genes. Ther...”

      Chromosomes and genes (article) | Khan Academy (4)

      Chromosomes and genes (article) | Khan Academy (5)

      Around 50,000 genes. There are also 24 chromosomes (groups of genes) in every cell.

      (25 votes)

  • Shlok Mamidi

    a year agoPosted a year ago. Direct link to Shlok Mamidi's post “How is DNA formed?”

    How is DNA formed?

    (3 votes)

    • Constant Blais

      a year agoPosted a year ago. Direct link to Constant Blais's post “DNA, or deoxyribonucleic ...”

      Chromosomes and genes (article) | Khan Academy (9)

      Chromosomes and genes (article) | Khan Academy (10)

      DNA, or deoxyribonucleic acid, is formed through a process called DNA replication. DNA replication occurs during the cell division process known as the S phase of the cell cycle. Here are the key steps involved:

      1. Initiation: The DNA double helix unwinds and separates into two strands. An enzyme called DNA helicase breaks the hydrogen bonds between the base pairs, causing the DNA strands to separate and form a replication fork.

      2. Primer Binding: Primers, which are short RNA sequences, are synthesized and bind to the DNA template strands. These primers provide a starting point for DNA synthesis.

      3. Elongation: DNA polymerase, an enzyme, attaches to the primer and begins synthesizing new DNA strands. It reads the template strand and adds complementary nucleotides to each growing daughter strand. Adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G), maintaining the base pairing rules.

      4. Leading and Lagging Strand Synthesis: DNA replication occurs in a semi-discontinuous manner due to the antiparallel nature of the DNA strands. The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in small fragments called Okazaki fragments. These fragments are later joined together.

      5. Termination: Once the entire DNA molecule has been replicated, termination signals halt the replication process. The DNA strands are fully synthesized, and the new double-stranded DNA molecules are ready for further cellular processes.

      DNA replication is a highly precise and complex process that ensures accurate transmission of genetic information from one generation of cells to the next. It plays a crucial role in the growth, development, and reproduction of organisms.

      (33 votes)

  • MorganD

    2 years agoPosted 2 years ago. Direct link to MorganD's post “why do some kids look lik...”

    why do some kids look like there grandparerents?

    (8 votes)

    • Maddie Horne

      2 years agoPosted 2 years ago. Direct link to Maddie Horne's post “yeah like he said, you ca...”

      Chromosomes and genes (article) | Khan Academy (14)

      yeah like he said, you can look like just about any family member. genes get passed. even people back in the day that you were related to, just a small chance.

      (12 votes)

  • Hermen

    2 years agoPosted 2 years ago. Direct link to Hermen's post “what's the difference bet...”

    what's the difference between Adams and molecules

    (2 votes)

    • SP

      2 years agoPosted 2 years ago. Direct link to SP's post “I think you mean atoms :)...”

      Chromosomes and genes (article) | Khan Academy (18)

      I think you mean atoms :)

      If you are talking about Adams, be informed that all things are made up of atoms, so all Adams are made up of atoms.

      If you do mean atoms, the thing is, molecules are made up of atoms. For example, a molecule may contain 2 hydrogen atoms and 1 oxygen atom. This creates a water molecule.

      (22 votes)

  • ya girl nini

    a year agoPosted a year ago. Direct link to ya girl nini's post “Why do some kids look lik...”

    Why do some kids look like their dad more than there mom?

    (5 votes)

    • Constant Blais

      a year agoPosted a year ago. Direct link to Constant Blais's post “According to a study publ...”

      According to a study published in Scientific American, babies tend to look more like their fathers than their mothers. This is because fathers are less certain that a baby is theirs and are more likely to invest whatever resources they have in their own offspring. However, there is no scientific evidence that supports this claim.

      Another theory suggests that genetics cause people to look and behave more like their dads than their moms. This is because children inherit half of their genetic material from each parent, and some traits are determined by genes on the sex chromosomes (X and Y). Since males have only one X chromosome, they will pass on all of their X-linked genes to their daughters but none to their sons. On the other hand, females have two X chromosomes, so they will pass on one of their X chromosomes to both their sons and daughters.

      It's important to note that while some children may resemble one parent more than the other, this does not mean that they are more related to one parent than the other. Children inherit half of their genetic material from each parent, so they are equally related to both parents.

      (9 votes)

  • Wolfy

    2 years agoPosted 2 years ago. Direct link to Wolfy's post “I see many questions abou...”

    I see many questions about genes and appearance, so I will try to explain some. Your gender (you being male or female), is decided by your mother and father's genes, whether you have XX chromosomes, which make you female, or XY chromosomes, which make you male.
    Now, along with this, your father and mother's genes which are passed onto you, do a fun sort of dance while you are in your mother's womb, to create entirely new combinations to make an entirely new person, which is you!

    Why do some people look like one parent or the other? One parent may have stronger genes then the other parent, so certain traits are more visible or apparent, which is why some people look very like the parent with stronger genes, but this does not mean you are like that parent in every way because genes decide much more then appearance, just because you look like, say, your dad, doesn't mean you act like him, or have the same health he does. Some people are a mix of their parents.

    Sometimes, kids look like their grandparents, or a grandparent, in this case, it's likely that your grandparent's genes, which are carried their child, which is your parent, has been passed to you, and they just strongly show in you.

    (7 votes)

    • Johanna

      2 years agoPosted 2 years ago. Direct link to Johanna's post “Thanks for sharing this. ...”

      Thanks for sharing this. You might want to put each answer under its question, even though that could take more time. This post is technically in the wrong category, and I don’t want your post just taken down or anything.

      I was wondering about how you said parents’ genes “do a fun sort of dance while you are in your mother's womb, to create entirely new combinations.” It was my understanding that one parent’s genes combine with themselves during meiosis. Then both parents’ genes combine during fertilization, which is what makes you (the zygote). The genes don’t combine while you’re in utero, but they do eventually combine to make you, right?

      (3 votes)

  • momothemoos

    2 years agoPosted 2 years ago. Direct link to momothemoos's post “if a cell can multipluy ...”

    if a cell can multipluy and the genes are in the cell do the genes multipluy

    (4 votes)

    • Adonalsium

      2 years agoPosted 2 years ago. Direct link to Adonalsium's post “Yes, the genes do multipl...”

      Yes, the genes do multiply, and the genes get cloned as part of the process. As people age, however, this process gets more difficult for the body, which is why when people get older they stop growing.

      (7 votes)

  • DonavenH

    10 months agoPosted 10 months ago. Direct link to DonavenH's post “can your DNA change throu...”

    can your DNA change through experiments

    (4 votes)

    • Velociraptor105

      10 months agoPosted 10 months ago. Direct link to Velociraptor105's post “Yes. DON'T try it, unless...”

      Yes. DON'T try it, unless you're absolutely positively certain that you know what you're doing.

      (5 votes)

  • lillian.olsey

    9 months agoPosted 9 months ago. Direct link to lillian.olsey's post “what happens if you have ...”

    what happens if you have too little chromosomes?

    (4 votes)

    • Poryguy-[INACTIVE FOR SUMMER]

      9 months agoPosted 9 months ago. Direct link to Poryguy-[INACTIVE FOR SUMMER]'s post “You cannot have "_too lit...”

      You cannot have "too little chromosomes." You can have different numbers* but not too little.

      *In different species.

      (3 votes)

  • Ludovica

    a year agoPosted a year ago. Direct link to Ludovica's post “Can we change the genes o...”

    Can we change the genes of a person also after the birth?

    (2 votes)

    • Gladiator(Rat #1)

      a year agoPosted a year ago. Direct link to Gladiator(Rat #1)'s post “Gene therapy , or somatic...”

      Gene therapy , or somatic gene editing, changes the DNA in cells of an adult or child to treat disease, or even to try to enhance that person in some way. The changes made in these somatic (or body) cells would be permanent but would only affect the person treated.

      (6 votes)

Chromosomes and genes (article) | Khan Academy (2024)

References

Top Articles
Latest Posts
Article information

Author: Jerrold Considine

Last Updated:

Views: 6337

Rating: 4.8 / 5 (58 voted)

Reviews: 89% of readers found this page helpful

Author information

Name: Jerrold Considine

Birthday: 1993-11-03

Address: Suite 447 3463 Marybelle Circles, New Marlin, AL 20765

Phone: +5816749283868

Job: Sales Executive

Hobby: Air sports, Sand art, Electronics, LARPing, Baseball, Book restoration, Puzzles

Introduction: My name is Jerrold Considine, I am a combative, cheerful, encouraging, happy, enthusiastic, funny, kind person who loves writing and wants to share my knowledge and understanding with you.