Topic 2 exam 1 Flashcards
What are the two types of cells found in eukaryotic organisms?
Somatic cells and gametes (sperm & egg)
What are chromosomes?
DNA + Protein & Chromatin
When are chromosomes visible?
cell division
Where are chromosomes found?
nucleus
What are the two types of chromosomes?
?
What are homologous pairs?
2 chromosomes that look the same because they carry a gene for the same trait
What is DNA
deoxiribinucleaicacid
What are the functions of DNA?
Copies itself, makes proteins and directs development
What is the structure and composition of DNA?
- double stranded helix
- The legs of the ladder alternate sugar and phosphate molecules
- Rungs paired nitrogen bases linked by a weak hydrogen bond
What the hell are nucleotides?
Each unit of sugar, phosphate and nitrogen base
Haploid
Number of homologous pairs (gametes)
Diploid
full number of chromosomes (somatic cell)
what are the bases?
Adenine, guanine, cytosine and thymine
Whats a codon
specifies an amino acid
How does RNA differ from DNA?
Sugar is ribose, the base uracil is substituted for thymine and it is single stranded
What are proteins?
Composed of amino acids also called polypeptide chains
What are amino acids?
organic compound
What is a polypeptide chain?
It is a chain of amino acids which is the DNA “codes for” proteins (proteins)
What is the genetic code?
Universal, redundant (repetitive)
How does protein synthesis work?
- Transcription ( same message diff format) DNA to mRNA in nucleus
- Translation (completely changing it) mRNA to protein in sytoplasm
Protein synthesis- Transcription
occurs in the nucleus
make mRNA from DNA
mRNA free flowing
Protein Synthesis- Translation
- occurs in the cytoplasm on ribosomes
- makes protein from mRNA
- at ribosome mRNA codons are translated into an amino acid
- ends when a stop codon is reached
What is mitosis?
Somatic cell division in which a single cell divides to produce two identical daughter cells (2 diploid daughter cells)
What is meiosis?
Cell division that occurs in the testes and ovaries that leads to the formation of sperm and gametes (4 haploid daughter cells)
Mitosis= Interphase
DNA replication
Mitosis Prophase
chromosome form
spindle fibers form
centrioles go to poles
membrane disappears
Mitosis= metaphase
alignment of center
Mitosis= anaphase
chromatids split
Mitosis= telophase
cell divides
What is the most important phase in Meiosis?
prophase
Meiosis 1
homologous chromatids divide
Meiosis 2
sister chromatids divide
How is meiosis and mitosis different?
Meiosis has two rounds of genetic separation and cell division while mitosis has only one of each, Mitosis daughter cells are identical and in Meiosis daughter cells not genetically identical
how does recombination occur in Meiosis
Random arrangement during metaphase 1
crossing over during prophase 1
How does meiosis differ with males and females?
Males: Sperm antogenesis, testes, continous, 4 sperm cells 22 autosomes
Females: oogenesis, ovaries, monthly, 1 large ovum (egg) and 3 “polar bodies”, 22 autosomes
how many chromosomes do humans have?
46
What is nondisjuntion
Miscarriage, when the chromatids fail to separate properly during cell division. May have extra gametes or missing ones
What is a zygote?
a fertilized egg
What do diploid and haploid refer to?
number of chromosomes
