B13: Reproduction Flashcards
what is
sexual reproduction?
- fusion of 2 gametes
- formation of gametes involves MEIOSIS
what is
asexual reproduction
-ony one parent reuqired so NO FUSION OF GAMETES
-offspring are genetically identical to parents/eachother (clones)
- uses MITOSIS
PROCESS OF MEIOSIS?
1) each chomosome is DUPLICATED, forming X chromosomes
2)first division:chromosome pairs line up along centre of cell/pulled apart so each new cell has one copy of each chromosome
3)second division: chromosome lines up in centre of cell/arms of chromosomes pulled apart
4) 4 haploid daughter cells produced - have half the genetic material of parent cell
importance of meiosis ?
produces gametes
inreases genetic variation in offpspring
AD AND DIS OF SEXUAL REPRODUCTION?
AD : increase genetic variation
- the species can adapt to new environemnts bc variation
- disease less likely bc of variation
DIS : takes time and energy to find mates
- difficult for isolated species to reproduce
AD and DIS of asexual reproduction?
ad: - Population can be increased rapidly
- more time and energy efficient
- faster than sexual reproduction
DIS : - no genetic variation
- vulnerable to chnages in eviron
- disease is likely to affect
what ORGANISMS use both types of reproduction and how ?
MALARIAL PARASITES : asexually in human host, sexually in mosquito
FUNGI : spores are produced both ways
PLANTS : seeds are produced either way
what is the genome?
entire set of genetic material of an organism is a GENOME
what is a gene?
short length of DNA found on chromosome
- each gene codes for particular sequnce of amino acids
why is the HUMAN GENOME PROJECT an important breakthrough?
- helps find treatemnts for genetic disorders
- can undertant human migration patterns from past
what are NUCLEOTIDES? and what do they consist of ?
induvidual subunits of DNA
- CONSISTS OF : -sugar and phsophate groups
- one of the four bases attached to phosphate
what codes for amino acids ?
a sequence of 3 bases is code for PARTICULAR AMINO ACID
-order of bases controls order/different types of amino acids
Function of ribosomes?
ribosomes ‘read’ code on the mRNA in groups of 3
- base code is transcibed onto an RNA molecule called messenger RNA (mRNA)
- mRNA can move out nucleus and attached to ribosome
- carrier molecules bring specific amino acids to add to growing protein chain
- ribosome translates sequence of bases into sequence of amino acids
- once amino acids have been assembled, relased from ribosome to fold/form a protein
proteins function?
ENZYMES
HORMONES
STRUCTURAL PROTEINS - provide structure/strong (eg collagen)
what are mutations?
random changes that occur in the sequence of DNA bases in a gene/chromosome
- can sometime slead to chnage in protein (as dna bases are changed)
types of mutations?
INSERTIONS : - new base inserted into DNA sequence
- changes amino acid that would have been coded for by the 3 bases
- can change the groups of 3 bases further in the DNA sequence
DELETIONS : - base is randomly deleted from DNA sequence
- changes amino aicd that would have been made
- changes group of 3 bases aswell
SUBSTITUTIONS: - base is randomly swapped for a different base
- only changes the group of 3 bases in which the MUTATION OCCURS (not further in the DNA sequence)
effects of mutations?
only small no. mutations code for significantly altered protein with differerent shape –> affect ability to perform funtion ( active site can change/lose strength)
what happens if mutation occurs in non-coding DNA ?
the expression of genes are altered/ may not be expressed at all
define
allele and the 2 types?
different verison of a particular gene
DOMINANT: always expressed
RECESSIVE : only expressed if two copies present
difference between GENOTYPE AND PHENOTYPE?
GENOTYPE: combination of alleles that control each charcteristic
PHENOTYPE: observable characteristics of an organism
what is Polydactyly and the cause?
havinge extra fingers/toes
- caused by DOMINANT ALLELE
What is CYSTIC FIBROSIS and cause?
- disorder of cell membranes , resulting in thick mucus in airways and pancreas
- RECESSIVE ALLELE - both parents have to be carriers , or one has CF /the other is a carrier
arguments for embryonic screening?
- reduce no. ppl suffering
- treatement is expensive
- many regulation to stop it form getting out of hand
arguments againts embryonic screening?
- could encourage DESIGNER BABIES
- expensive
- promote prejudice - those iwth disorder cant live as long/unwanted
- decision to terminate pregnancy need to made
- can lead to miscarrage
whch pair of chromosmes carry sex determining genes/ what do females and males carry?
23rd
FEMALE : XX
MALE : XY
what is embryonic screening?
IVF is where embryos fertilised in lab /implanted into mom’s womb
- cell taken from embryo to analyse genes before implanting
- detects for genetic disorders
