heredity and DNA review

38 terms by sabrinalr5

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Ms. goldshmidt 7th grade


A piece of DNA that determines a specific trait.


A form of a gene


Organism's entire set of DNA


strands of DNA


The process of cell division used to produce sex calls with one set of chromosomes.

Double helix

DNA in the shape of a twisted ladder

Adenine, Thymine, Cytosine, Guanine

Four nitrogen bases found in DNA. Adenine pairs with Thymine and Cytosine pairs with guanine.

Nitrogen base

Their order determines what trait you will have.

Phosphate group and Deoxyribose

The sides of the double helix. They are in a alternating pattern that goes, deoxyribose (sugar) then phosphate group then deoxyribose (sugar) then phosphate etc.


One phosphate group, one deoxyribose, and one nitrogen bases.


A changes in a gene or chromosome


When one base pair is substitution for another


When one base pair is removed


When one bases pair is added

Protein synthesis

Is the process used to take information from the gene determines what proteins will be produced.


a group of three nitrogen bases.


stands for message ribonucleic acid which carries the code from the DNA out of the nucleus.


stands for Transfer ribonucleic acid which carries the amino acids to the ribosomes

1.What is the role of DNA in an organism?

DNA directs an organism's traits and activities.

2. What is the relationship between genetic traits and the environment?

The traits are determined by an individual DNA and its interactions with the environment. EX. Height is controlled by genes, but can also be affected by nutrition.

3. Explain the relationship between genes, alleles, and chromosomes.

In each body cell 23 pairs of chromosomes contain thousands of genes. Alleles, which are a form of a gene, control how a gene will be expressed.

4. Describe the chromosomes found in a human body cell. Why do you have two of each chromosome?

The chromosomes found in a human body cell contain thousands of genes. The chromosomes come in identical pair s of 23 because you get a pair from your mother and a pair from your father.

5. What is a sex cell? How is it different from a body cell? Why must it be different?

Sex cells, eggs and sperm, are different from body cells because they only contain one set of DNA. They only contain one set because when they come together, they form a full two sets of DNA, which is now able to produce an offspring.

6. & 7. How are traits with two alleles determined?

Dominant Recessive- one form of the gene is dominant over the other. The dominant

8. Describe how traits for single genes with more than two alleles can be determined.

There are more than two possible alleles for the gene but each individual gene still has only two alleles (one on each of the two chromosomes with that gene.)

9. What is the full name of DNA?

Deoxyribonucleic acid.

10. Name and describe the components of DNA.

DNA is made up of 4 different nitrogen bases, Adenine, Thymine, Guanine, and Cytosine, that always pair together horozantally across a strand of DNA Adenine with Thymine and Guanine with Cytosine in a random order that are a chemical code that controls living things traits. Lining either side of DNA are an alternating pattern of deoxyribose (sugar) and phosphate groups.

11. Describe the structure and shape of a DNA molecule.

A DNA molecule is the shape of a twisted ladder, or a double helix.

12. State how the bases pair in a DNA molecule.

The bases pair as follows:

13. Explain how DNA contains a "code" (information).

The order in which the base pairs are randomly arranged in DNA determines every specific trait about a living thing.

15. Can all mutations be passed on to an organism's offspring? Explain why or why not.

Only mutations in sex cells can be passed on to offspring. This is because an offspring gets a randomly selected half of its parent's chromosomes, which are held in sex cells. This does not mean, however, that all sex-lin ked mutations are passed on to offspring.

16. Describe the two main types of mutation

The two main types of mutations are changes of nitrogenous bases, which can happen during DNA replication (Substitution, Addition & Deletion), and changes of chromosomes, which can happen when chromosomes don't separate correctly during meiosis. This can produce cells with the wrong number of chromosomes.

17. Describe the three types of mutations that result from changes in nitrogen bases.Which of these are more likely to produce drastic effects? Why?

The three main types of mutation that are a result of changes in nitrogen bases are substitution, when a base pair is put in place of another base pair, addition, when a base pair is added into a random place of the DNA molecule, and deletion, when a random base pair is taken out of the DNA molecule. Addition and Deletion cause the most drastic effects because these types of mutation cause all codons after the addition or deletion to shift, leading to codons being read differently and sending insufficient messages to an organism.

18. A mutation's effects can be harmful, helpful, or neutral. What do these descriptions mean?

Mutations can be either harmful to an organism, meaning it decreases the chances for an organism to survive and reproduce, helpful, meaning it increases the chances for an organism to survive and reproduce, or neutral, meaning it does not interfere with an organisms normal chances to survive and reproduce.

19. Describe some possible causes of mutations.

UV radiation can increase your chances of skin cancer. Errors in DNA replication or repair can increase your chances of mutations.

20) Describe the process of protein synthesis in detail

The process of protein synthesis is the code in DNA is translated to mRNA which takes the code to the ribosomes and turns them into proteins.

21) Why is mRNA necessary for the protein synthesis

mRNA is necessary for the protein synthesis because mRNA gets the code out of the nucleus into the ribosome

22. What are the three key differences between DNA and RNA?

1) RNA has only one strand, instead of two. 2) RNA contains uracil instead of thymine. 3) RNA has the sugar ribose instead of deoxyribose.

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