unit 4 Flashcards
where is gametogenesis stored?
testes (seminiferous tubules)
where do sperm go to mature and be stored?
epididymis
what does the primary spermatocyte cell do?
meiosis
monomer of nucleic acids
nucleotide
What 3 parts to all nucleotides have?
a phosphate, sugar, and nitrogenous base
how many rings in purines?
2
how many rings in pyrimidines?
1
what bond links nucleotides?
phosphodiester bond
explain Chargaff’s ratio
ratio of A:T is always around 1, and the ratio of G:C is always around 1
what types of bonds are formed between the bases in double stranded DNA?
hydrogen bonds
One base is changed in the DNA sequence, but it doesn’t change the amino acid sequence
silent mutation
one base is changed in the DNA sequence that changes one amino acid in the sequence
missense mutation
one base is changed in the DNA sequence that changes one amino acid to a stop codon
nonsense mutation
addition of 1-2 bases in the DNA sequence, produces a different amino acid sequence
Frameshift
What are the 3 models of DNA replication?
conservative, dispersive, and semiconservative
explain conservative DNA replication
results in 2 DNA copies - one made of entirely new DNA and another made of the old DNA strands
explain semi-conservative DNA replication
results in 2 DNA copies, each with one strand of old DNA and one strand of new DNA
explain dispersive DNA replication
results in 2 DNA copies, each strand contains some new and old DNA
What is the correct DNA replication model?
Semi-conservative model
what enzyme makes DNA
DNA polymerase
How does DNA polymerase make DNA?
adds nucleotides onto the end of a nucleic acid (primer)
what strand is continuous in DNA replication?
leading strand
what strand is discontinuous in DNA replication?
lagging strand
what does DNA helicase do?
separates DNA strands by breaking hydrogen bonds
What type of mutation is sickle cell anemia?
missense
what is the goal of mitosis?
to generate two daughter cells identical to mother cell in chromosome content
What phase of mitosis does DNA replication occur?
S phase (technically before mitosis begins)
Define homologous chromosomes
same genes in same order on chromosome, but DNA sequences aren’t identical
define sister chromatids
when 1 chromosome is replicated and now you have 2 copies of that chromosome
what are the 5 stages of mitosis?
prophase, prometaphase, metaphase, anaphase, telophase
what is the mitotic spindle made of?
microtubules
What are the mitotic spindles responsible for during mitosis?
separating chromosomes
what happens in prophase in mitosis?
duplicated chromosomes condense
what is the kinetochore
a protein structure formed at the centromere
where are sister chromosomes joined?
at the centromere
what happens in prometaphase in mitosis?
- nuclear envelope completely fragments
- spindle fiber microtubules attach to centromere/kinetochore
what happens in metaphase in mitosis?
-chromosomes move back and forth until lined up at metaphase plate
-in a line in the middle
what happens in anaphase in mitosis?
- sister chromatids begin to be separated and move towards opposite poles
what happens in telophase in mitosis?
- chromosomes arrive at poles
cytokinesis
- making two cells from one
how do plants do cytokinesis?
- make cell plate
how do animals do cytokinesis?
- squeeze off the middle using actin filaments
what is the goal of meiosis?
Start out with a cell with two copies of each chromosome (diploid) (like a primary spermatocyte)
-Want to produce four cells, each with one copy of each chromosome (haploid) (like sperm)
what happens in prophase I in meisosis?
make bivalent / crossing over
does crossing over occur in mitosis or meiosis?
meiosis
what happens in meiosis I?
prophase I, pairs of homologous chromosomes migrate to metaphase plate, homologous chromosomes separate and move to opposite poles - end up in opposite cells after cytokinesis
what happens in meiosis II?
sister chromatids are separated into different cells
-outcome is 4 cells, each haploid,
