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Science Chapter 4 Sections 2 & 3
notes
21
Science
7th Grade
10/04/2011

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Term
What is it called when 2 sex cells, usually an egg and a sperm, come together?
Definition
sexual reproduction
Term
What is Fertilization?
Definition
the joining of an egg and a sperm, generally from 2 different organisms of the same species
Term
What are formed in the male reproductive organs?
Definition
sperm
Term
What are formed in the female reproductive organs?
Definition
eggs
Term
What is a zygote?
Definition
a cell that forms from fertilization
Term
What happens after ferilization?
Definition
cell division begins and a new organism developes
Term
Why are human body cells diploid?
Definition
because they have 23 pairs of similar chromosomes
Term
Are human sex cells haploid or diploid?
Definition
haploid
Term
Why are human sex cells haploid?
Definition
because they have 23 single chromosomes
Term
What is a process that produces haploid sex cells and ensures that offspring have the sam diploid number as its parents
Definition
meiosis
Term
What is a chemical that contains information that an organism needs to grow and function?
Definition
DNA
Term
When did Watson and Crick make an accurate model of DNA?
Definition
in 1953
Term
What is a the structure of DNA similar to?
Definition
a twisted ladder
Term
What are sections of DNA on a chromosome?
Definition
genes
Term
Genes contain instructions for making proteins from the nucleus to the ribosome which is where?
Definition
in the cytoplasm
Term
What brings amino acids to the ribosomes to build the protein?
Definition
Transfer RNA
Term
Where does Ribosomal NA make up ribosomes?
Definition
where proteins are built
Term
Cells use only the genes that do what in the making of proteins needed by that cell?
Definition
direct
Term
What are mutatationss?
Definition
any permanent change in the DNA sequence of a cell's genes or chromosomes
Term
What are 3 things that can be caused by outside factors?
Definition
-X rays
-sunlight
-some chemicals
Term
What happens if a change in a gene or chromosome occurs?
Definition
it can change the the traits of an organism
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