Genetics Flashcards
(33 cards)
Define a cell:
- Cells are the basic units of life in all living organisms
- in some forms such as bacteria, a single cell constitutes an entire organism
- Complex life forms, such as plants and animals are made up of billions of cells
- An adult human can consist of billions of cells, all functioning in complex ways that promote the survival of the individuals
Define a prokaryote:
-Life on earth can be traced back 3.7 billion years to primordial cell form of prokaryotic cells.
-Single-celled organisms, with DNA, RNA, proteins and small molecules (no membrane bound nucleus)
Ex:// bacteria and blue green alage
Define a eukaryote:
- Structurally more complex, appeared 1.2 billion years ago
- Include all members of the plant and animal kingdom
- membrane bound nucleus
What are the very important organelles (VIO)?
- Organelles are structures found in the cytoplasm
- Mitochondria: produce energy
- Ribosome: manufacture proteins
- Endoplasmic reticulum: synthesis and transport of lipids and membrane proteins
- Nucleus: surrounded by the cytoplasm and membrane. Contains chromosomal DNA
Describe Somatic cells:
- components of body tissue
- Diploid –carries full component of genome
Describe Gametes:
- sex cells
- haploid–one copy–1/2 compelement
- ova produced in femal ovaries, sperm produced in male testes
Describe Zygote:
-union between sperm and egg. 23 chromosomes from mom, 23 chromosomes from dad. Total of 46
Define Exon
- Protein coding region of DNA
- Exons are DNA segments transcribed into mRNA that code for specific amino acids.
Define Introns
- Non protein coding regiod of DNA
- Introns are DNA sequences not expressed during protein synthesis.
What happens to chromosomes during mitosis and meiosis?
How might these processes affect genetic variation?
Like mitosis, meiosis is a form of eukaryotic cell division. However, these two processes distribute genetic material among the resulting daughter cells in very different ways. Mitosis creates two identical daughter cells that each contain the same number of chromosomes as their parent cell. In contrast, meiosis gives rise to four unique daughter cells, each of which has half the number of chromosomes as the parent cell. Because meiosis creates cells that are destined to become gametes (or reproductive cells), this reduction in chromosome number is critical — without it, the union of two gametes during fertilization would result in offspring with twice the normal number of chromosomes!
Apart from this reduction in chromosome number, meiosis differs from mitosis in yet another way. Specifically, meiosis creates new combinations of genetic material in each of the four daughter cells. These new combinations result from the exchange of DNA between paired chromosomes. Such exchange means that the gametes produced through meiosis exhibit an amazing range of genetic variation.
Finally, unlike mitosis, meiosis involves two rounds of nuclear division, not just one.
Define Chromosome:
- structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
- Humans have 23 (22 autosomes, 1 sex) get 23 from each parent that organize in homologous pairs.
Define a gene:
-a region of DNA that contains information needed to make a functional piece of RNA
Genes consist of a promoter region, exons and introns.
1)Promoter region which tells RNA polymerase where to bind to the DNA (not transcribed)
2) Exons are DNA segments transcribed into mRNA that code for specific amino acids.
3) Introns are DNA sequences not expressed during protein synthesis.
Describe Telomeres:
- A telomere is a region of repetitive nucleotide sequences at each end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes.
- Dolly the sheep had issues because she had a telomere length of a sheep that was 6 yrs old.
Describe alleles:
-AN ALTERNATE FORM OF A GENE
-Humans have two copies or alleles of all autosomal
genes
-Alleles represent different DNA coding of a gene
-Genetic variation is caused by changes in DNA code
-Some changes in the DNA coding do not cause functional changes in phenotype
EX: change from an A to a T produces sickle cell anemia
What is the difference between facultative and constituative?
Faculative= gets triggered to get expressed
constituative=always expressed
Describe Gene Structure:
- Cellular function and an organism’s inheritance depends on the structure and function of DNA.
- DNA is composed of two chains of nucleotides.
- A nucleotide consists of a phosphate, a sugar, and one of four nitrogenous bases
What do we do with DNA?
- Replicate: make another copy and cell just like the original cell
- Make proteins for a variety of body building blocks to run the machinery
Describe the DNA Replication Process
- Enzymes break the bonds between the DNA molecule.
- Two nucleotide chains serve as templates for the formation of a new strand of nucleotides.
- Unattached nucleotides pair with the appropriate complementary nucleotide
- The result is two newly formed strands of DNA.
- Each new strand is joined to one of the original strands of DNA.
- This action is done in preparation for the formation of another identical cell in a process called MITOSIS
Describe Proteins:
- The major structural components of tissue.
- Proteins differ according to number of amino acids and the sequence in which they are arranged.
- Enzymes are proteins that serve as catalysts, initiating chemical reactions in the body.
- Amino acids are the building blocks of protein.
- Proteins differ according to number of amino acids and the sequence in which they are arranged
Describe Protein Synthesis:
- Ribosomes help convert the genetic message from the DNA into proteins.
- Messenger RNA (mRNA) carries the genetic message from the cell nucleus to the ribosome.
- Transfer RNA (tRNA), found in the cytoplasm, binds to one specific amino acid.
Describe the differences in RNA and DNA
RNA differs from DNA in important ways:
- It’s usually single-stranded.
- It contains a different type of sugar.
- It contains the base uracil as a substitute for the DNA base thymine. (Uracil is attracted to adenine, just as thymine is.)
- It can leave the nucleus of the cell
Describe transcription:
- The process of coding a genetic message for proteins by formation of mRNA.
- A portion of the DNA unwinds and serves as a template for the formation of a mRNA strand.
- DNA template or “sense strand” Strand of messenger RNA (mRNA) is built making a strand of complementary strand
- Strand exits nucleus through nuclear pores where it connects with ribosome
Describe translation:
- mRNA binds to ribosome, small particles of protein and rRNA
- Ribosome sandwiches the mRNA
- tRNAs arrive at the ribosome carrying their specific amino acids.
- The base triplets (anticodons) on the tRNA match up with the codons on the mRNA.
- As each tRNA line up in the sequence of mRNA codons their amino acids link to form a protein.
Describe the assembly of the amino acid chain in protein synthesis:
- As the ribosome binds to the mRNA, tRNA brings a particular amino acid, specified by the mRNA codon, to the ribosome.
- The tRNA binds to the first codon while a second tRNA–amino acid complex arrives at the ribosome.
- The ribosome moves down the mRNA, allowing a third amino acid to be brought into position by another tRNA molecule. Note that the first two amino acids are now joined together.
